build: Cancel in progress actions on update

If the PR updated cancel outstanding jobs to conserve resources.

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
(cherry picked from commit 1db30405e1)

.github/workflows/docker-image.yaml

@@ -5,6 +5,9 @@ on:
     paths: resources/Dockerfile
   pull_request:
     paths: resources/Dockerfile
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 env:
   REGISTRY: ghcr.io