Bump appengine-testing from 1.9.38 to 2.0.6

Bumps appengine-testing from 1.9.38 to 2.0.6.

---
updated-dependencies:
- dependency-name: com.google.appengine:appengine-testing
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

build.gradle

@@ -53,7 +53,7 @@ dependencies {
     testImplementation 'com.google.appengine:appengine-api-1.0-sdk:1.9.38'
     testImplementation 'com.google.appengine:appengine-api-labs:1.9.38'
     testImplementation 'com.google.appengine:appengine-api-stubs:1.9.38'
-    testImplementation 'com.google.appengine:appengine-testing:1.9.38'
+    testImplementation 'com.google.appengine:appengine-testing:2.0.6'
     testImplementation 'com.squareup.okhttp:okhttp:2.7.5'
     testImplementation 'com.squareup.okhttp3:okhttp:4.0.0'
     testImplementation 'com.google.guava:guava:19.0'