Added docker container workflow

.forgejo/workflows/docker.yml

@@ -0,0 +1,39 @@
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  docker:
+    runs-on: docker
+    container:
+      image: ghcr.io/catthehacker/ubuntu:full-latest
+    steps:
+      - name: Setup Docker Buildx
+        uses: https://code.forgejo.org/docker/setup-buildx-action@v3
+
+      - name: Docker Metadata
+        id: meta
+        uses: https://code.forgejo.org/docker/metadata-action@v5
+        with:
+          images: gnarwhal/motto
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+
+      - name: Login to package registry
+        uses: https://code.forgejo.org/docker/login-action@v3
+        with:
+          registery: forge.monodon.me
+          username: ${{ github.actor }}
+          password: ${{ github.token }}
+          
+      - name: Build and push
+        uses: https://code.forgejo.org/docker/build-push-action@v6
+        with:
+          platforms: linux/amd64,linux/arm64
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}