👷 add workflow for building docker image

.gitea/workflows/ci.yaml

@@ -0,0 +1,35 @@
+name: ci
+
+on:
+  push:
+    branches:
+      - "main"
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    services:
+      registry:
+        image: registry:2
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Log in to the Container registry
+        uses: docker/login-action@v2
+        with:
+          registry: gitea.pimux.de
+          username: ${{ secrets.MY_GITEA_USERNAME }}
+          password: ${{ secrets.MY_GITEA_TOKEN }}
+      - name: Build and push to local registry
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          push: true
+          tags: gitea.pimux.de/finn/reminder:latest
+      - name: Inspect
+        run: |
+          docker buildx imagetools inspect gitea.pimux.de/finn/reminder:latest