Add more precise optional dependency to cncf.kubernetes from flink (#…

…29707)

The Flink provider has an optional cncf.kubernetes depedency that
requires cncf.kubernetes at least in version 5.1.0 (some new features
of the classes in cncf.kubernetes are used in Flink on Kubernetes.

airflow/providers/apache/flink/provider.yaml

@@ -54,3 +54,8 @@ sensors:
   - integration-name: Apache Flink
     python-modules:
       - airflow.providers.apache.flink.sensors.flink_kubernetes
+
+additional-extras:
+  - name: cncf.kubernetes
+    dependencies:
+      - apache-airflow-providers-cncf-kubernetes>=5.1.0