deps: update dependency org.openjdk.jmh:jmh-core to v1.25 (#382)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| org.openjdk.jmh:jmh-core | minor | `1.24` -> `1.25` |

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google-cloud-spanner/pom.xml

@@ -306,7 +306,7 @@
     <dependency>
       <groupId>org.openjdk.jmh</groupId>
       <artifactId>jmh-core</artifactId>
-      <version>1.24</version>
+      <version>1.25</version>
       <scope>test</scope>
     </dependency>
     <dependency>