deps: update dependency org.openjdk.jmh:jmh-core to v1.28 (#923)

Author: renovate-bot

Diff for: google-cloud-spanner/pom.xml

@@ -304,7 +304,7 @@
     <dependency>
       <groupId>org.openjdk.jmh</groupId>
       <artifactId>jmh-core</artifactId>
-      <version>1.27</version>
+      <version>1.28</version>
       <scope>test</scope>
     </dependency>
     <dependency>