Update dependency com.google.cloud:google-cloud-core to v2.8.1

Author: renovate-bot

pom.xml

@@ -382,7 +382,7 @@ limitations under the License.
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-core</artifactId>
-      <version>2.6.1</version>
+      <version>2.8.1</version>
       <scope>test</scope>
       <classifier>tests</classifier>
     </dependency>