Upgrade pydantic version (#168)

Why
===

Our pydantic version is getting a little out of date, and we were
pinning to a specific version.

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

Made the package less proscriptive regarding pydantic version, and
changed minimum python version to 3.12.

Test plan
=========

CI/CD

Author: JimmyAustin

pyproject.toml

@@ -6,7 +6,7 @@ authors = [{ name = "Replit", email = "[email protected]" }]
 license = { file = "LICENSE" }
 keywords = ["rpc", "websockets"]
 readme = "README.md"
-requires-python = ">=3.11,<4"
+requires-python = ">=3.12,<4"
 classifiers = [
   "Development Status :: 4 - Beta",
 
@@ -20,7 +20,7 @@ classifiers = [
   "Programming Language :: Python :: 3.12",
 ]
 dependencies = [
-    "pydantic==2.9.2",
+    "pydantic>=2.9.0,<3",
     "aiochannel>=1.2.1",
     "grpcio-tools>=1.59.3",
     "grpcio>=1.59.3",