ci: commit uv.lock for reproducible installs

uv.lock was gitignored, so CI had no lockfile and uv sync re-resolved to
the latest (including the broken hypothesis 6.161.7). Commit the lock and
stop ignoring it.

Author: dannywillems

.gitignore

@@ -128,7 +128,6 @@ dmypy.json
 # Pyre type checker
 .pyre/
 
-uv.lock
 # Tooling caches and generated artifacts
 .ruff_cache/
 sbom.cdx.json