fix(top-level): use patch-package to fix depd-vs-SES incompatibility

Some packages try to modify properties that SES freezes, like
`Error.prepareStackTrace`. These packages cannot be imported in a SES
environment. Work is underway to tolerate these (endojs/endo#251).

`depd` is one such package. As a temporary workaround, this uses the
`patch-package` tool to modify the installed `depd` code during the `yarn
install` process, patching out its attempt to mutate frozen primordials. When
that bug is fixed, we should remove this change.

package.json

@@ -62,9 +62,12 @@
     "lint-fix": "yarn workspaces run lint-fix",
     "lint-check": "yarn workspaces run lint-check",
     "test": "yarn workspaces run test",
-    "build": "yarn workspaces run build"
+    "build": "yarn workspaces run build",
+    "postinstall": "patch-package"
   },
   "dependencies": {
-    "@agoric/store": "^0.1.2"
+    "@agoric/store": "^0.1.2",
+    "patch-package": "^6.2.2",
+    "postinstall-postinstall": "^2.1.0"
   }
 }