Fix Python SDK protobuf compatibility lower bound (#240)

* Tighten our compat bound

* Include uv.lock update from compat bound tightening

The lock file was not staged in afed8c0, leaving it out of sync
with pyproject.toml.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: comnik

sdks/python/pyproject.toml

@@ -13,7 +13,7 @@ authors = [
 ]
 requires-python = ">=3.10"
 dependencies = [
-    "protobuf>=3.20.3,<6.0.0",
+    "protobuf>=5.28,<6.0.0",
 ]
 
 [project.scripts]