chore(deps): update dependency com.google.cloud:libraries-bom to v26.4.0 (#569)

Author: renovate-bot

samples/snapshot/pom.xml

@@ -28,7 +28,7 @@
  <dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>libraries-bom</artifactId>
- <version>26.3.0</version>
+ <version>26.4.0</version>
  <type>pom</type>
  <scope>import</scope>
  </dependency>

samples/snippets/pom.xml

@@ -28,7 +28,7 @@
  <dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>libraries-bom</artifactId>
- <version>26.3.0</version>
+ <version>26.4.0</version>
  <type>pom</type>
  <scope>import</scope>
  </dependency>