chore(deps): update dependency com.google.cloud:libraries-bom to v21 (#1351)

Author: renovate-bot

samples/snippets/pom.xml

@@ -33,7 +33,7 @@
  <dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>libraries-bom</artifactId>
- <version>20.9.0</version>
+ <version>21.0.0</version>
  <type>pom</type>
  <scope>import</scope>
  </dependency>