deps: update dependency com.google.cloud:google-cloud-monitoring-bom to v3.8.0 (#1548)

[![Mend Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.cloud:google-cloud-monitoring-bom](https://togithub.com/googleapis/google-cloud-java) | `3.7.0` -> `3.8.0` | [![age](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-monitoring-bom/3.8.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-monitoring-bom/3.8.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-monitoring-bom/3.8.0/compatibility-slim/3.7.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.cloud:google-cloud-monitoring-bom/3.8.0/confidence-slim/3.7.0)](https://docs.renovatebot.com/merge-confidence/) |

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

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

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

🔕 **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 [Mend Renovate](https://www.mend.io/free-developer-tools/renovate/). View repository job log [here](https://app.renovatebot.com/dashboard#github/googleapis/java-bigtable).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNC4yNC4wIiwidXBkYXRlZEluVmVyIjoiMzQuMjQuMCJ9-->

Author: renovate-bot

google-cloud-bigtable-deps-bom/pom.xml

@@ -73,7 +73,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-monitoring-bom</artifactId>
-        <version>3.7.0</version>
+        <version>3.8.0</version>
         <exclusions>
           <exclusion>
             <!-- using the perfmark version in opencensus -->