Bump grpcio from 1.53.0 to 1.53.2 in /docs

Bumps [grpcio](https://github.com/grpc/grpc) from 1.53.0 to 1.53.2.
- [Release notes](https://github.com/grpc/grpc/releases)
- [Changelog](https://github.com/grpc/grpc/blob/master/doc/grpc_release_schedule.md)
- [Commits](grpc/grpc@v1.53.0...v1.53.2)

---
updated-dependencies:
- dependency-name: grpcio
  dependency-type: direct:production
...

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

docs/requirements.txt

@@ -47,7 +47,7 @@ fs==2.4.12
 gast==0.5.2
 google-auth==2.14.1
 google-auth-oauthlib==0.4.6
-grpcio==1.53.0
+grpcio==1.53.2
 h11==0.14.0
 helpdev==0.7.1
 html5lib==1.1