add workflow to build and push image to ghcr

.github/workflows/ghcr.yml

@@ -0,0 +1,39 @@
+name: ghcr ci
+
+env:
+  DOTNET_VERSION: '6.0.x'
+  IMAGE_NAME: 'btc-rpc-proxy'
+
+on:
+  push:
+    tags:
+      - v*
+
+jobs:
+      push-image:
+        runs-on: ubuntu-latest
+        permissions:
+          packages: write
+          contents: read
+        steps:
+          - uses: actions/checkout@v4
+          - name: Set up Docker Buildx
+            uses: docker/setup-buildx-action@v2
+          - name: Build image
+            run: docker buildx build . --tag $IMAGE_NAME --label "runnumber=${GITHUB_RUN_ID}"
+          - name: Log in to registry
+            run: echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u ${{ github.actor }} --password-stdin
+
+          - name: Push image
+            run: |
+              IMAGE_ID=ghcr.io/${{ github.repository_owner }}/$IMAGE_NAME
+              IMAGE_ID=$(echo $IMAGE_ID | tr '[A-Z]' '[a-z]')
+              VERSION=$(echo "${{ github.ref }}" | sed -e 's,.*/\(.*\),\1,')
+              [[ "${{ github.ref }}" == "refs/tags/"* ]] && VERSION=$(echo $VERSION | sed -e 's/^v//')
+              [ "$VERSION" == "main" ] && VERSION=latest
+              echo IMAGE_ID=$IMAGE_ID
+              echo VERSION=$VERSION
+              docker tag $IMAGE_NAME $IMAGE_ID:$VERSION
+              docker push $IMAGE_ID:$VERSION
+          - name: Clean up Docker images
+            run: docker image prune -f