CI: add workflow for publishing Docker image

.github/workflows/publish-image.yml

@@ -0,0 +1,33 @@
+name: Publish Docker image to ghcr.io
+
+permissions:
+  packages: write
+
+on:
+  push:
+    tags:
+      - 'v*'
+  pull_request:
+
+jobs:
+  test:
+    name: Publish image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v4
+
+      - uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: kobzol
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - uses: docker/setup-buildx-action@v3
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          platforms: linux/amd64,linux/arm64
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ghcr.io/kobzol/cargo-pgo:latest
+          # ghcr.io/kobzol/cargo-pgo:${{ github.ref_name }},