Bump grpc-stubs from 1.53.0.5 to 1.53.0.6

Bumps [grpc-stubs](https://github.com/shabbyrobe/grpc-stubs) from 1.53.0.5 to 1.53.0.6.
- [Commits](shabbyrobe/grpc-stubs@1.53.0.5...1.53.0.6)

---
updated-dependencies:
- dependency-name: grpc-stubs
  dependency-version: 1.53.0.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

pyproject.toml

@@ -72,7 +72,7 @@ dev-mkdocs = [
 dev-mypy = [
   "mypy == 1.15.0",
   # This dependency introduces breaking changes in patch releases
-  "grpc-stubs == 1.53.0.5",
+  "grpc-stubs == 1.53.0.6",
   "types-Markdown == 3.8.0.20250415",
   # For checking the noxfile, docs/ script, and tests
   "frequenz-dispatch[dev-mkdocs,dev-noxfile,dev-pytest]",