Update docker/build-push-action digest to 1556069 (#1752)

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

.github/workflows/build_linux.yaml

@@ -116,7 +116,7 @@ jobs:
 
             # This allows contributors to test changes to the dockerbuild image within a pull request
             - name: Build docker image
-              uses: docker/build-push-action@31159d49c0d4756269a0940a750801a1ea5d7003 # v6
+              uses: docker/build-push-action@15560696de535e4014efeff63c48f16952e52dd1 # v6
               if: steps.changed_files.outputs.any_modified == 'true'
               with:
                   context: dockerbuild