Add builder image, fix runners

.gitea/workflows/build-builder-docker.yml

@@ -0,0 +1,22 @@
+name: Build and Push Builder Image
+
+# Trigger this workflow when we change the Dockerfile
+on:
+  push:
+    paths:
+      - 'docker/Dockerfile'
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+
+      - name: Login to Gitea Container Registry
+        run: docker login git.dws.rip -u ${{ gitea.actor }} -p ${{ secrets.GLOBAL_TOKEN }}
+      - name: Build and Push Image
+        run: |
+          IMAGE_TAG="git.dws.rip/dws/chrony-builder:latest"
+          docker build -t $IMAGE_TAG -f docker/Dockerfile .
+          docker push $IMAGE_TAG