Upgrade protobuf dependency (#109)

Why
===

The rest of the python ecosystem is on protobuf 5, let's upgrade so we
aren't stuck with old dependencies.

What changed
============

- Upgrade protobuf to v5

Test plan
=========

- Codegen should still work

Author: cbrewster

pyproject.toml

@@ -20,15 +20,15 @@ classifiers = [
   "Programming Language :: Python :: 3.12",
 ]
 dependencies = [
-	"pydantic==2.9.2",
+    "pydantic==2.9.2",
     "aiochannel>=1.2.1",
     "black>=23.11,<25.0",
     "grpcio-tools>=1.59.3",
     "grpcio>=1.59.3",
     "msgpack-types>=0.3.0",
     "msgpack>=1.0.7",
     "nanoid>=2.0.0",
-    "protobuf>=4.24.4",
+    "protobuf>=5.28.3",
     "pydantic-core>=2.20.1",
     "websockets>=12.0",
 ]