Bump com.google.cloud:google-cloud-bigtable in /modules/gcloud

Bumps [com.google.cloud:google-cloud-bigtable](https://github.com/googleapis/java-bigtable) from 2.9.0 to 2.18.3.
- [Release notes](https://github.com/googleapis/java-bigtable/releases)
- [Changelog](https://github.com/googleapis/java-bigtable/blob/main/CHANGELOG.md)
- [Commits](googleapis/java-bigtable@v2.9.0...v2.18.3)

---
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] <support@github.com>

Author: dependabot[bot]

modules/gcloud/build.gradle

@@ -7,6 +7,6 @@ dependencies {
     testImplementation 'com.google.cloud:google-cloud-firestore:3.2.0'
     testImplementation 'com.google.cloud:google-cloud-pubsub:1.120.0'
     testImplementation 'com.google.cloud:google-cloud-spanner:6.25.7'
-    testImplementation 'com.google.cloud:google-cloud-bigtable:2.9.0'
+    testImplementation 'com.google.cloud:google-cloud-bigtable:2.18.3'
     testImplementation 'org.assertj:assertj-core:3.23.1'
 }