Add anthropicInferenceTest Gradle task without wiring to inferencePostCommitIT

Define the task so it can be invoked manually or wired in later once
an ANTHROPIC_API_KEY secret is available in Apache CI.

Addresses review feedback from @jrmccluskey.

Author: bvolpato

sdks/python/test-suites/dataflow/common.gradle

@@ -537,6 +537,34 @@ task geminiInferenceTest {
     }
 }
 
+// Anthropic RunInference IT tests
+task anthropicInferenceTest {
+  dependsOn 'initializeForDataflowJob'
+  dependsOn ':sdks:python:sdist'
+  def requirementsFile = "${rootDir}/sdks/python/apache_beam/ml/inference/anthropic_tests_requirements.txt"
+  doFirst {
+      exec {
+        executable 'sh'
+        args '-c', ". ${envdir}/bin/activate && pip install -r $requirementsFile"
+      }
+    }
+  doLast {
+      def testOpts = basicTestOpts
+      def argMap = [
+          "test_opts": testOpts,
+          "suite": "AnthropicTests-df-py${pythonVersionSuffix}",
+          "collect": "anthropic_postcommit" ,
+          "runner": "TestDataflowRunner",
+          "requirements_file": "$requirementsFile"
+      ]
+      def cmdArgs = mapToArgString(argMap)
+      exec {
+        executable 'sh'
+        args '-c', ". ${envdir}/bin/activate && ${runScriptsDir}/run_integration_test.sh $cmdArgs"
+      }
+    }
+}
+
 task installTFTRequirements {
   dependsOn 'initializeForDataflowJob'
   doLast {