Add missing Forgejo Action build config.

.forgejo/workflows/build.yaml

@@ -0,0 +1,20 @@
+name: build
+run-name: ${{ forgejo.actor }} is building
+on:
+  push:
+    branches: [main]
+
+jobs:
+  build:
+    runs-on: host
+    env:
+      IMAGE_NAME: projects.torsion.org/witten/wake-on-lan-service:latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - run: podman login --username "$USERNAME" --password "$PASSWORD" projects.torsion.org
+        env:
+          USERNAME: "${{ secrets.REGISTRY_USERNAME }}"
+          PASSWORD: "${{ secrets.REGISTRY_PASSWORD }}"
+      - run: podman build --tag "$IMAGE_NAME" --storage-opt "overlay.mount_program=/usr/bin/fuse-overlayfs" .
+      - run: podman push "$IMAGE_NAME"