Remove redundant checks for asyncio.CancelledError

Author: kristjanvalur

redis/asyncio/connection.py

@@ -491,8 +491,6 @@ async def read_from_socket(
             # data was read from the socket and added to the buffer.
             # return True to indicate that data was read.
             return True
-        except asyncio.CancelledError:
-            raise
         except (socket.timeout, asyncio.TimeoutError):
             if raise_on_timeout:
                 raise TimeoutError("Timeout reading from socket") from None
@@ -711,7 +709,7 @@ async def connect(self):
                 lambda: self._connect(), lambda error: self.disconnect()
             )
         except asyncio.CancelledError:
-            raise
+            raise  # in 3.7 and earlier, this is an Exception, not BaseException
         except (socket.timeout, asyncio.TimeoutError):
             raise TimeoutError("Timeout connecting to server")
         except OSError as e: