Update rabbitmq

Changes:

- https://github.com/docker-library/rabbitmq/commit/472f9f9: Update 3.8-rc to 3.8.12-beta.1

library/rabbitmq

@@ -4,6 +4,26 @@ Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Joseph Ferguson <[email protected]> (@yosifkit)
 GitRepo: https://github.com/docker-library/rabbitmq.git
 
+Tags: 3.8.12-beta.1, 3.8-rc
+Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
+GitCommit: 472f9f92501efc8678fdb62944905e9c2b9d5167
+Directory: 3.8-rc/ubuntu
+
+Tags: 3.8.12-beta.1-management, 3.8-rc-management
+Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
+GitCommit: 7e63843da6bfb191ddee6dbe3dd7ec0df36ae70b
+Directory: 3.8-rc/ubuntu/management
+
+Tags: 3.8.12-beta.1-alpine, 3.8-rc-alpine
+Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
+GitCommit: 472f9f92501efc8678fdb62944905e9c2b9d5167
+Directory: 3.8-rc/alpine
+
+Tags: 3.8.12-beta.1-management-alpine, 3.8-rc-management-alpine
+Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
+GitCommit: 7e63843da6bfb191ddee6dbe3dd7ec0df36ae70b
+Directory: 3.8-rc/alpine/management
+
 Tags: 3.8.11, 3.8, 3, latest
 Architectures: amd64, arm32v7, arm64v8, i386, ppc64le, s390x
 GitCommit: 8622e40c638f26a8f3bd9f04cf5be104605bf6b6