Client update needed to match REST spec changes

[client-library-maintainer]

A diff between this client library's spec and our hosted spec was found. The client may need an update to match any changes in our API. See the diff below:

--- https://raw.githubusercontent.com/polygon-io/client-python/master/.polygon/rest.json
+++ https://api.polygon.io/openapi
@@ -24562,10 +24562,6 @@
                 },
                 "schema": {
                   "properties": {
-                    "next_url": {
-                      "description": "If present, this value can be used to fetch the next page of data.",
-                      "type": "string"
-                    },
                     "request_id": {
                       "type": "string"
                     },
@@ -24591,78 +24587,44 @@
                           "session": {
                             "properties": {
                               "change": {
-                                "description": "The value of the price change for the contract from the previous trading day.",
+                                "description": "The value of the change for the index from the previous trading day.",
                                 "format": "double",
                                 "type": "number"
                               },
                               "change_percent": {
-                                "description": "The percent of the price change for the contract from the previous trading day.",
+                                "description": "The percent of the change for the index from the previous trading day.",
                                 "format": "double",
                                 "type": "number"
                               },
                               "close": {
-                                "description": "The closing price for the asset of the day.",
+                                "description": "The closing value for the index of the day.",
                                 "format": "double",
                                 "type": "number"
                               },
-                              "early_trading_change": {
-                                "description": "Today’s early trading change amount, difference between price and previous close if in early trading hours, otherwise difference between last price during early trading and previous close.",
-                                "format": "double",
-                                "type": "number"
-                              },
-                              "early_trading_change_percent": {
-                                "description": "Today’s early trading change as a percentage.",
-                                "format": "double",
-                                "type": "number"
-                              },
                               "high": {
-                                "description": "The highest price for the asset of the day.",
+                                "description": "The highest value for the index of the day.",
                                 "format": "double",
                                 "type": "number"
                               },
-                              "late_trading_change": {
-                                "description": "Today’s late trading change amount, difference between price and today’s close if in late trading hours, otherwise difference between last price during late trading and today’s close.",
-                                "format": "double",
-                                "type": "number"
-                              },
-                              "late_trading_change_percent": {
-                                "description": "Today’s late trading change as a percentage.",
-                                "format": "double",
-                                "type": "number"
-                              },
                               "low": {
-                                "description": "The lowest price for the asset of the day.",
+                                "description": "The lowest value for the index of the day.",
                                 "format": "double",
                                 "type": "number"
                               },
                               "open": {
-                                "description": "The open price for the asset of the day.",
+                                "description": "The open value for the index of the day.",
                                 "format": "double",
                                 "type": "number"
                               },
                               "previous_close": {
-                                "description": "The closing price for the asset of previous trading day.",
+                                "description": "The closing value for the index of previous trading day.",
                                 "format": "double",
                                 "type": "number"
-                              },
-                              "volume": {
-                                "description": "The trading volume for the asset of the day.",
-                                "format": "double",
-                                "type": "number"
                               }
                             },
-                            "required": [
-                              "change",
-                              "change_percent",
-                              "close",
-                              "high",
-                              "low",
-                              "open",
-                              "previous_close"
-                            ],
                             "type": "object",
                             "x-polygon-go-type": {
-                              "name": "Session"
+                              "name": "IndicesSession"
                             }
                           },
                           "ticker": {

[justinpolygon]

Closing - the majority of this should be cleared up shortly. Some via #434 and others via a bug fix in the upstream spec file that's outside of the scope of this library.