ci: add publish workflow (#227)

Author: jokerttu

.github/workflows/publish.yml

@@ -0,0 +1,33 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# A workflow that publishes the library to CocoaPods
+name: Publish to pub.dev
+
+on:
+  push:
+    tags:
+      - "v[0-9]+.[0-9]+.[0-9]+"
+  workflow_dispatch: # manually trigger if previous runs failed
+
+concurrency:
+  group: publishing
+  cancel-in-progress: true
+
+# Publish using the reusable workflow from dart-lang.
+jobs:
+  publish:
+    permissions:
+      id-token: write # Required for authentication using OIDC
+    uses: dart-lang/setup-dart/.github/workflows/publish.yml@v1