Bump com.google.cloud:google-cloud-core-http in /plugins/repository-gcs

Bumps com.google.cloud:google-cloud-core-http from 2.17.0 to 2.21.1.

---
updated-dependencies:
- dependency-name: com.google.cloud:google-cloud-core-http
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

plugins/repository-gcs/build.gradle

@@ -66,7 +66,7 @@ dependencies {
   api 'com.google.code.gson:gson:2.9.0'
   api 'com.google.api.grpc:proto-google-common-protos:2.10.0'
   api 'com.google.api.grpc:proto-google-iam-v1:0.12.0'
-  api 'com.google.cloud:google-cloud-core-http:2.17.0'
+  api 'com.google.cloud:google-cloud-core-http:2.21.1'
   api "com.google.auth:google-auth-library-credentials:${versions.google_auth}"
   api "com.google.auth:google-auth-library-oauth2-http:${versions.google_auth}"
   api 'com.google.oauth-client:google-oauth-client:1.33.3'