gha: don't fail if no daemon.json is present

CI failed sometimes if no daemon.json was present:

    Run sudo rm /etc/docker/daemon.json
    sudo rm /etc/docker/daemon.json
    sudo service docker restart
    docker version
    docker info
    shell: /usr/bin/bash -e {0}
    env:
    DESTDIR: ./build
    BUILDKIT_REPO: moby/buildkit
    BUILDKIT_TEST_DISABLE_FEATURES: cache_backend_azblob,cache_backend_s3,merge_diff
    BUILDKIT_REF: 798ad6b0ce9f2fe86dfb2b0277e6770d0b545871
    rm: cannot remove '/etc/docker/daemon.json': No such file or directory
    Error: Process completed with exit code 1.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.github/workflows/buildkit.yml

@@ -106,7 +106,7 @@ jobs:
       -
         name: Update daemon.json
         run: |
-          sudo rm /etc/docker/daemon.json
+          sudo rm -f /etc/docker/daemon.json
           sudo service docker restart
           docker version
           docker info