Bump com.google.cloud:libraries-bom from 26.65.0 to 26.68.0

Bumps [com.google.cloud:libraries-bom](https://github.com/googleapis/java-cloud-bom) from 26.65.0 to 26.68.0.
- [Release notes](https://github.com/googleapis/java-cloud-bom/releases)
- [Changelog](https://github.com/googleapis/java-cloud-bom/blob/main/release-please-config.json)
- [Commits](googleapis/java-cloud-bom@v26.65.0...v26.68.0)

---
updated-dependencies:
- dependency-name: com.google.cloud:libraries-bom
  dependency-version: 26.68.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

pom.xml

@@ -33,7 +33,7 @@
         <maven.compiler.release>21</maven.compiler.release>
 
         <skipITs>true</skipITs>
-        <version.gcp.librariesbom>26.65.0</version.gcp.librariesbom>
+        <version.gcp.librariesbom>26.68.0</version.gcp.librariesbom>
         <version.gcp.bigquerybom>2.55.0</version.gcp.bigquerybom>
         <!-- Plugin versions -->
         <version.assembly.plugin>3.7.1</version.assembly.plugin>