added gitea docker registry workflow

.gitea/workflows/docker-publish.yml

@@ -0,0 +1,33 @@
+name: Publish Docker Image
+
+on:
+  push:
+    branches:
+      - prod
+
+jobs:
+  docker:
+    runs-on: docker  # make sure your Gitea runner supports Docker
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Gitea Container Registry
+        run: |
+          echo "${{ secrets.REGISTRY_TOKEN }}" | docker login gitea.mrmoku.de -u ${{ secrets.REGISTRY_USER }} --password-stdin
+
+      - name: Get Git commit SHA
+        id: commit_sha
+        run: echo "COMMIT_SHA=$(git rev-parse --short HEAD)" >> $GITHUB_ENV
+
+      - name: Build Docker image
+        run: |
+          docker build -t gitea.mrmoku.de/${{ secrets.REGISTRY_USER }}/bttersplit:${{ env.COMMIT_SHA }} .
+
+      - name: Push Docker image
+        run: |
+          docker push gitea.mrmoku.de/${{ secrets.REGISTRY_USER }}/bettersplit:${{ env.COMMIT_SHA }}