Bump grpcio-tools from 1.49.1 to 1.50.0 in /test/environment/grpc (#342)

Bumps [grpcio-tools](https://grpc.io) from 1.49.1 to 1.50.0.

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

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test/environment/grpc/requirements.txt

@@ -1,4 +1,4 @@
-grpcio-tools==1.49.1
+grpcio-tools==1.50.0
 grpcio==1.50.0
 grpcio-reflection==1.49.1
 grpcio-health-checking==1.49.1