Bump org.threeten:threetenbp in /plugins/repository-gcs

Bumps [org.threeten:threetenbp](https://github.com/ThreeTen/threetenbp) from 1.4.4 to 1.6.9.
- [Release notes](https://github.com/ThreeTen/threetenbp/releases)
- [Changelog](https://github.com/ThreeTen/threetenbp/blob/main/RELEASE-NOTES.md)
- [Commits](ThreeTen/threetenbp@v1.4.4...v1.6.9)

---
updated-dependencies:
- dependency-name: org.threeten:threetenbp
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

plugins/repository-gcs/build.gradle

@@ -85,7 +85,7 @@ dependencies {
   api "commons-logging:commons-logging:${versions.commonslogging}"
   api "org.apache.logging.log4j:log4j-1.2-api:${versions.log4j}"
   api "commons-codec:commons-codec:${versions.commonscodec}"
-  api 'org.threeten:threetenbp:1.4.4'
+  api 'org.threeten:threetenbp:1.6.9'
   api 'io.grpc:grpc-api:1.57.2'
   api 'io.opencensus:opencensus-api:0.31.1'
   api 'io.opencensus:opencensus-contrib-http-util:0.31.1'