ci: automate quic-network-simulator docker image build & push

.github/workflows/interop-docker.yml

@@ -0,0 +1,31 @@
+name: qns (quic-network-simulator)
+
+on:
+  push:
+    branches:
+      - 'docker' # TODO: update
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      # TODO: needed?
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ github.token }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          push: true
+          tags: mxinden/neqo-qns:latest
+          path: qns/