chore: Update docker:dind Docker digest to a56b3bd

Author: grafanarenovatebot[bot]

.github/workflows/build_and_publish.yaml

@@ -49,7 +49,7 @@ jobs:
       id-token: none
     services:
       docker:
-        image: docker:dind@sha256:c0872aae4791ff427e6eda52769afa04f17b5cf756f8267e0d52774c99d5c9de
+        image: docker:dind@sha256:a56b3bdde89315ed2cc0e4906e582b5033d93bf20d9cb9510c2cdd4e7f7690b1
         options: --privileged --shm-size=2g
         volumes:
           - /var/run/docker.sock:/var/run/docker.sock:ro