chore(deps): update dependency org.apache.maven.plugins:maven-site-plugin to v3.12.1 (#2122)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [org.apache.maven.plugins:maven-site-plugin](https://maven.apache.org/plugins/) | `3.12.0` -> `3.12.1` | [![age](https://badges.renovateapi.com/packages/maven/org.apache.maven.plugins:maven-site-plugin/3.12.1/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/maven/org.apache.maven.plugins:maven-site-plugin/3.12.1/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/maven/org.apache.maven.plugins:maven-site-plugin/3.12.1/compatibility-slim/3.12.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/maven/org.apache.maven.plugins:maven-site-plugin/3.12.1/confidence-slim/3.12.0)](https://docs.renovatebot.com/merge-confidence/) |

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google-api-client-bom/pom.xml

@@ -137,7 +137,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-site-plugin</artifactId>
-        <version>3.12.0</version>
+        <version>3.12.1</version>
         <configuration>
           <skip>true</skip>
         </configuration>

pom.xml

@@ -322,7 +322,7 @@
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-site-plugin</artifactId>
-          <version>3.12.0</version>
+          <version>3.12.1</version>
         </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>