Can't test grpc examples with Java 21+ currently

Because of lightbend/ssl-config#367
Exception:
java.lang.IllegalArgumentException: GrpcClientSettings requires a server endpoint with ssl, but none provided

.github/workflows/build-test.yml

@@ -154,7 +154,8 @@ jobs:
     needs: changes
     if: ${{ (github.event_name != 'pull_request' && !failure() && !cancelled()) || contains(fromJSON(needs.changes.outputs.samples), 'java-grpc')}}
     with:
-      java: 17, 21
+      # Can't test with Java 21+ currently because of https://github.com/lightbend/ssl-config/issues/367
+      java: 17
       scala: 2.13.x, 3.x
       gradle-build-root: play-java-grpc-example
       add-dimensions: >-
@@ -336,7 +337,8 @@ jobs:
     needs: changes
     if: ${{ (github.event_name != 'pull_request' && !failure() && !cancelled()) || contains(fromJSON(needs.changes.outputs.samples), 'scala-grpc')}}
     with:
-      java: 17, 21
+      # Can't test with Java 21+ currently because of https://github.com/lightbend/ssl-config/issues/367
+      java: 17
       scala: 2.13.x, 3.x
       gradle-build-root: play-scala-grpc-example
       add-dimensions: >-