fix(deps): update dependency com.google.protobuf:protobuf-bom to v3.2…

…1.5 (#1772)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.protobuf:protobuf-bom](https://developers.google.com/protocol-buffers/) ([source](https://togithub.com/protocolbuffers/protobuf)) | `3.21.4` -> `3.21.5` | [![age](https://badges.renovateapi.com/packages/maven/com.google.protobuf:protobuf-bom/3.21.5/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.protobuf:protobuf-bom/3.21.5/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.protobuf:protobuf-bom/3.21.5/compatibility-slim/3.21.4)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.protobuf:protobuf-bom/3.21.5/confidence-slim/3.21.4)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

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

### [`v3.21.5`](https://togithub.com/protocolbuffers/protobuf/compare/v3.21.4...v3.21.5)

[Compare Source](https://togithub.com/protocolbuffers/protobuf/compare/v3.21.4...v3.21.5)

</details>

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gax-java/pom.xml

@@ -162,7 +162,7 @@
       <dependency>
         <groupId>com.google.protobuf</groupId>
         <artifactId>protobuf-bom</artifactId>
-        <version>3.21.4</version>
+        <version>3.21.5</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>