Update CI

.github/workflows/build-image.yml

@@ -7,7 +7,24 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    permissions:
+      packages: write
     steps:
-    - uses: actions/checkout@v3
+      - name: Set up Docker Buildx
-    - name: Build the Docker image
+        uses: docker/setup-buildx-action@v3
-      run: docker build . --tag papermc:$(date +%s)
+
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          push: true
+          tags: ghcr.io/${{ github.repository }}
+          labels: org.opencontainers.image.source=https://github.com/${{ github.repository }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max