Schedule a nightly cron job for build+push of containers

Signed-off-by: Anoop C S <anoopcs@samba.org>

.github/workflows/nightly-run.yml

@@ -0,0 +1,37 @@
+name: Nightly CI
+
+on:
+  schedule:
+    - cron: '0 2 * * *'
+
+jobs:
+
+  build-nightly-server:
+    runs-on: ubuntu-latest
+    env:
+      BUILDAH_FORMAT: oci
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build the nightly server image
+      run: make build-nightly-server
+
+  test-nightly-server:
+    #needs: build-nightly-server
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Test the nightly server image
+      run: make test-nightly-server
+
+  push:
+
+    # verify it passes build and test first
+    needs: test-nightly-server
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: log in to quay.io
+        run: podman login -u "${{ secrets.QUAY_USER }}" -p "${{ secrets.QUAY_PASS }}" quay.io
+      - name: push nightly server image
+        # note: forcing use of podman here, since we did podman login above
+        run: make CONTAINER_CMD=podman push-nightly-server