deps: update gax.version to v2.12.2 (#592)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [com.google.api:gax-grpc](https://togithub.com/googleapis/gax-java) | `2.11.0` -> `2.12.2` | [![age](https://badges.renovateapi.com/packages/maven/com.google.api:gax-grpc/2.12.2/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.api:gax-grpc/2.12.2/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.api:gax-grpc/2.12.2/compatibility-slim/2.11.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.api:gax-grpc/2.12.2/confidence-slim/2.11.0)](https://docs.renovatebot.com/merge-confidence/) |
| [com.google.api:gax-bom](https://togithub.com/googleapis/gax-java) | `2.11.0` -> `2.12.2` | [![age](https://badges.renovateapi.com/packages/maven/com.google.api:gax-bom/2.12.2/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/com.google.api:gax-bom/2.12.2/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/com.google.api:gax-bom/2.12.2/compatibility-slim/2.11.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/com.google.api:gax-bom/2.12.2/confidence-slim/2.11.0)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>googleapis/gax-java</summary>

### [`v2.12.2`](https://togithub.com/googleapis/gax-java/blob/HEAD/CHANGELOG.md#&#8203;2122-httpsgithubcomgoogleapisgax-javacomparev2121v2122-2022-02-09)

[Compare Source](https://togithub.com/googleapis/gax-java/compare/v2.12.1...v2.12.2)

### [`v2.12.1`](https://togithub.com/googleapis/gax-java/blob/HEAD/CHANGELOG.md#&#8203;2121-httpsgithubcomgoogleapisgax-javacomparev2120v2121-2022-02-09)

[Compare Source](https://togithub.com/googleapis/gax-java/compare/v2.12.0...v2.12.1)

### [`v2.12.0`](https://togithub.com/googleapis/gax-java/blob/HEAD/CHANGELOG.md#&#8203;2120-httpsgithubcomgoogleapisgax-javacomparev2110v2120-2022-01-28)

[Compare Source](https://togithub.com/googleapis/gax-java/compare/v2.11.0...v2.12.0)

##### Features

-   add REST interceptors infrastructure ([#&#8203;1607](https://togithub.com/googleapis/gax-java/issues/1607)) ([0572eed](https://togithub.com/googleapis/gax-java/commit/0572eed8aa29879c74794b22e8ae79e414dd5821))

</details>

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first-party-dependencies/pom.xml

@@ -56,7 +56,7 @@
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <site.installationModule>${project.artifactId}</site.installationModule>
     <grpc.version>1.44.1</grpc.version>
-    <gax.version>2.11.0</gax.version>
+    <gax.version>2.12.2</gax.version>
     <grpc-gcp.version>1.1.0</grpc-gcp.version>
     <guava.version>31.0.1-jre</guava.version>
     <protobuf.version>3.19.4</protobuf.version>