Bump grpcio from 1.51.0 to 1.51.1 in /test/environment/grpc

Bumps [grpcio](https://github.com/grpc/grpc) from 1.51.0 to 1.51.1.
- [Release notes](https://github.com/grpc/grpc/releases)
- [Changelog](https://github.com/grpc/grpc/blob/master/doc/grpc_release_schedule.md)
- [Commits](grpc/grpc@v1.51.0...v1.51.1)

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

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

test/environment/grpc/requirements.txt

@@ -1,5 +1,5 @@
 grpcio-tools==1.50.0
-grpcio==1.51.0
+grpcio==1.51.1
 grpcio-reflection==1.50.0
 grpcio-health-checking==1.50.0
 grpcio-testing==1.50.0