chore(java): make org.graalvm.buildtools:junit-platform-native a test dependency upgrade in renovate (#1922)

Author: kolea2

synthtool/gcp/templates/java_library/renovate.json

@@ -68,7 +68,8 @@
         "^com.google.truth:truth",
         "^org.mockito:mockito-core",
         "^org.objenesis:objenesis",
-        "^com.google.cloud:google-cloud-conformance-tests"
+        "^com.google.cloud:google-cloud-conformance-tests",
+        "^org.graalvm.buildtools:junit-platform-native"
       ],
       "semanticCommitType": "test",
       "semanticCommitScope": "deps"