Add release step (#9)

.github/workflows/ci.yml

@@ -68,3 +68,31 @@ jobs:
 
       - name: Run cargo tests
         run: cargo test --all-features
+
+  check:
+    if: always()
+    needs: [test, lint]
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check if all needed jobs succeeded
+        uses: re-actors/alls-green@release/v1
+        with:
+          jobs: ${{ toJSON(needs) }}
+
+  release:
+    needs: [check]
+    if: "success() && startsWith(github.ref, 'refs/tags/')"
+    runs-on: ubuntu-latest
+    environment: release
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install Rust stable
+        uses: dtolnay/rust-toolchain@stable
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Publish to crates.io
+        run: cargo publish
+        env:
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}