Enable automated publishing (#73)

.github/workflows/publish.yml

@@ -0,0 +1,23 @@
+name: Publish to pub.dev
+
+on:
+  push:
+    tags:
+      - '[0-9]+.[0-9]+.[0-9]+*'
+
+jobs:
+  publish:
+    name: Publish to pub.dev
+    runs-on: ubuntu-latest
+    environment: pub.dev
+    permissions:
+      id-token: write
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dart-lang/setup-dart@v1
+      - uses: subosito/flutter-action@v2
+        with:
+          channel: 'stable'
+      - run: flutter pub get
+      - name: Publish
+        run: flutter pub publish --force