deps: update dependency com.google.protobuf:protobuf-java to v3.21.6 (#…

…411)

[![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.protobuf:protobuf-java](https://developers.google.com/protocol-buffers/) ([source](https://togithub.com/protocolbuffers/protobuf)) | `3.21.5` -> `3.21.6` | [![age](https://badges.renovateapi.com/packages/maven/com.google.protobuf:protobuf-java/3.21.6/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.protobuf:protobuf-java/3.21.6/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.protobuf:protobuf-java/3.21.6/compatibility-slim/3.21.5)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.protobuf:protobuf-java/3.21.6/confidence-slim/3.21.5)](https://docs.renovatebot.com/merge-confidence/) |

---

### Release Notes

<details>
<summary>protocolbuffers/protobuf</summary>

### [`v3.21.6`](https://togithub.com/protocolbuffers/protobuf/compare/v3.21.5...v3.21.6)

[Compare Source](https://togithub.com/protocolbuffers/protobuf/compare/v3.21.5...v3.21.6)

</details>

---

### 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, click this checkbox.

---

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-common-protos).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzMi4xOTQuNSIsInVwZGF0ZWRJblZlciI6IjMyLjE5OC4xIn0=-->

proto-google-common-protos/build.gradle

@@ -18,7 +18,7 @@ repositories {
 }
 
 dependencies {
-  compile 'com.google.protobuf:protobuf-java:3.21.5'
+  compile 'com.google.protobuf:protobuf-java:3.21.6'
 }
 
 sourceSets {