[protobuf] Bump to 7.34.1 and improve type coverage

Signed-off-by: Emmanuel Ferdman <emmanuelferdman@gmail.com>

Author: emmanuel-ferdman

stubs/protobuf/@tests/stubtest_allowlist.txt

@@ -26,12 +26,17 @@ google.protobuf.descriptor.ServiceDescriptor.__new__
 # It's a hack - just allow it.
 google.protobuf.internal.containers.BaseContainer.__hash__
 
-# Metaclass differs:
-google.protobuf.descriptor.OneofDescriptor
-
 # Runtime does not have __iter__ (yet...): hack in spirit of https://github.com/python/typeshed/issues/7813
 google.protobuf.internal.well_known_types.ListValue.__iter__
 
 # It's a list at runtime, but if we do that pyright complains about incompatible overrides
 # in subclasses that use a tuple for __slots__.
 google.protobuf.message.Message.__slots__
+
+# Thin wrapper around the C extension metaclass; users should use
+# google.protobuf.reflection.GeneratedProtocolMessageType instead
+google.protobuf.pyext
+google.protobuf.pyext.cpp_message
+
+# Package with only __init__.py, no public API
+google.protobuf.testdata

stubs/protobuf/METADATA.toml

@@ -1,8 +1,8 @@
 # Using an exact number in the specifier for scripts/sync_protobuf/google_protobuf.py
 # When updating, also re-run the script
-version = "~=6.32.1"
+version = "~=7.34.1"
 upstream_repository = "https://github.com/protocolbuffers/protobuf"
-extra_description = "Partially generated using [mypy-protobuf==3.6.0](https://github.com/nipunn1313/mypy-protobuf/tree/v3.6.0) and libprotoc 31.1 on [protobuf v32.1](https://github.com/protocolbuffers/protobuf/releases/tag/v32.1) (python `protobuf==6.32.1`)."
+extra_description = "Partially generated using [mypy-protobuf==3.6.0](https://github.com/nipunn1313/mypy-protobuf/tree/v3.6.0) and libprotoc 34.1 on [protobuf v34.1](https://github.com/protocolbuffers/protobuf/releases/tag/v34.1) (python `protobuf==7.34.1`)."
 partial_stub = true
 
 [tool.stubtest]