Bump google-cloud-bigtable from 2.5.2 to 2.6.1 in /modules/gcloud

Bumps [google-cloud-bigtable](https://github.com/googleapis/java-bigtable) from 2.5.2 to 2.6.1.
- [Release notes](https://github.com/googleapis/java-bigtable/releases)
- [Changelog](https://github.com/googleapis/java-bigtable/blob/main/CHANGELOG.md)
- [Commits](googleapis/java-bigtable@v2.5.2...v2.6.1)

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

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

Author: dependabot[bot]

modules/gcloud/build.gradle

@@ -7,6 +7,6 @@ dependencies {
     testImplementation 'com.google.cloud:google-cloud-firestore:3.0.14'
     testImplementation 'com.google.cloud:google-cloud-pubsub:1.115.1'
     testImplementation 'com.google.cloud:google-cloud-spanner:6.20.0'
-    testImplementation 'com.google.cloud:google-cloud-bigtable:2.5.2'
+    testImplementation 'com.google.cloud:google-cloud-bigtable:2.6.1'
     testImplementation 'org.assertj:assertj-core:3.22.0'
 }