deps: update dependency org.openjdk.jmh:jmh-core to v1.24 (#375)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| org.openjdk.jmh:jmh-core | minor | `1.23` -> `1.24` |

---

### Renovate configuration

:date: **Schedule**: At any time (no schedule defined).

:vertical_traffic_light: **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

:recycle: **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

:no_bell: **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [WhiteSource Renovate](https://renovate.whitesourcesoftware.com). View repository job log [here](https://app.renovatebot.com/dashboard#googleapis/java-spanner).

Author: renovate-bot

google-cloud-spanner/pom.xml

@@ -305,7 +305,7 @@
     <dependency>
       <groupId>org.openjdk.jmh</groupId>
       <artifactId>jmh-core</artifactId>
-      <version>1.23</version>
+      <version>1.24</version>
       <scope>test</scope>
     </dependency>
     <dependency>