Bump grpcio-tools from 1.38.0 to 1.38.1 in /tests

Bumps [grpcio-tools](https://github.com/grpc/grpc) from 1.38.0 to 1.38.1.
- [Release notes](https://github.com/grpc/grpc/releases)
- [Changelog](https://github.com/grpc/grpc/blob/master/doc/grpc_release_schedule.md)
- [Commits](grpc/grpc@v1.38.0...v1.38.1)

---
updated-dependencies:
- dependency-name: grpcio-tools
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

tests/requirements.txt

@@ -13,4 +13,4 @@ pytest-profiling==1.7.0
 more-itertools==8.8.0
 mock==4.0.3
 grpcio==1.38.0
-grpcio-tools==1.38.0
+grpcio-tools==1.38.1