ci: add release workflows (#15)

Author: HomelessDinosaur

.github/workflows/publish.yaml

@@ -0,0 +1,23 @@
+name: Publish to pub.dev
+
+on:
+  push:
+    tags:
+      - "v[0-9]+.[0-9]+.[0-9]+*" # tag pattern on pub.dev: 'v{{version}'
+
+# Publish using custom workflow
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dart-lang/setup-dart@v1
+      - name: Install dependencies
+        run: dart pub get
+      - name: Check Publish Warnings
+        run: dart pub publish --dry-run
+      - name: Publish
+        uses: k-paxian/dart-package-publisher@v1.5.1
+        with:
+          credentialJson: ${{ secrets.CREDENTIAL_JSON }}
+          skipTests: true

.github/workflows/release.yaml

@@ -0,0 +1,23 @@
+name: Release
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  release:
+    name: semantic-release
+    runs-on: ubuntu-20.04
+    outputs:
+      new-release-published: ${{ steps.semantic-release.outputs.new_release_published }}
+      new-release-version: ${{ steps.semantic-release.outputs.new_release_version }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          persist-credentials: false
+      - id: semantic-release
+        uses: cycjimmy/semantic-release-action@v4
+        env:
+          GITHUB_TOKEN: ${{ secrets.NITRIC_BOT_TOKEN }}