Bump io.grpc:grpc-context in /plugins/repository-gcs

Bumps [io.grpc:grpc-context](https://github.com/grpc/grpc-java) from 1.46.0 to 1.56.1.
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.46.0...v1.56.1)

---
updated-dependencies:
- dependency-name: io.grpc:grpc-context
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

plugins/repository-gcs/build.gradle

@@ -86,7 +86,7 @@ dependencies {
   api "org.apache.logging.log4j:log4j-1.2-api:${versions.log4j}"
   api "commons-codec:commons-codec:${versions.commonscodec}"
   api 'org.threeten:threetenbp:1.4.4'
-  api 'io.grpc:grpc-context:1.46.0'
+  api 'io.grpc:grpc-context:1.56.1'
   api 'io.opencensus:opencensus-api:0.31.1'
   api 'io.opencensus:opencensus-contrib-http-util:0.31.1'