chore(deps): update vexxhost/docker-atmosphere digest to 56b3dda (#964)

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/build.yml

@@ -25,7 +25,7 @@ jobs:
         with:
           egress-policy: audit
 
-      - uses: vexxhost/docker-atmosphere/.github/actions/build-image@a1ad25c00b6bbf44621748b3a9ed664c6b6cf929 # main
+      - uses: vexxhost/docker-atmosphere/.github/actions/build-image@56b3dda2bc9f2e464de8997bdafd998cdb1e54a2 # main
         with:
           image-name: python-openstackclient
           push: ${{ github.event_name != 'pull_request' }}