[chore] Fix uv publishing (#108)

Why
===

I missed the significance of `--locked` vs `--frozen` when setting up
for publishing.

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

- Using `--frozen` to _verify_ `uv.lock` but permit metadata changes
(like the package `version` that gets updated prior to publishing)
- Adding missing package classifiers

Test plan
=========

Can we publish? Can we install? Does the installed package work?

.github/workflows/python-publish.yml

@@ -43,7 +43,7 @@ jobs:
 
     - name: Build and publish
       run: |
-        uv sync --locked
+        uv sync --frozen  # NB: Not --locked, since bumping the version changes the lockfile.
         uv build
         UV_PUBLISH_TOKEN="${{ secrets.PYPI_TOKEN }}" \
         uv publish

pyproject.toml

@@ -6,7 +6,19 @@ authors = [{ name = "Replit", email = "[email protected]" }]
 license = { file = "LICENSE" }
 keywords = ["rpc", "websockets"]
 readme = "README.md"
-requires-python = ">=3.11"
+requires-python = ">=3.11,<4"
+classifiers = [
+  "Development Status :: 4 - Beta",
+
+  "Intended Audience :: Developers",
+  "Topic :: Internet",
+
+  "License :: OSI Approved :: MIT License",
+
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: 3.12",
+]
 dependencies = [
 	"pydantic==2.9.2",
     "aiochannel>=1.2.1",