add forgejo actions workflow for container building

.forgejo/workflows/container.yml

@@ -0,0 +1,29 @@
+name: Build Container
+
+on:
+  push: {}
+
+permissions:
+  packages: write
+
+jobs:
+  build-container:
+    name: Build Container
+    runs-on: docker
+    container:
+      image: ghcr.io/osscontainertools/kaniko:alpine
+    steps:
+      - name: Build Container
+        env:
+          KANIKO_NO_PUSH: ${{ forgejo.ref_name != 'main' }}
+        run:  /kaniko/executor \
+          --dockerfile "${{ forgejo.workspace }}/Containerfile" \
+          --context-dir="dir://${{ forgejo.workspace }}" \
+          --destination=${{ forgejo.server_url }}/${{ forgejo.repository }}:latest \
+          --credential-helpers=env \
+          --no-push-cache \
+          --annotation=org.opencontainers.image.ref.name=dooris \
+          --annotation=org.opencontainers.image.url=${{ forgejo.server_url }}/${{ forgejo.repository }} \
+          --annotation=org.opencontainers.image.source=${{ forgejo.server_url }}/${{ forgejo.repository }} \
+          --annotation=org.opencontainers.image.licenses=AGPL-3.0
+