Add Changelog workflow

.github/workflows/changelog.yml

@@ -0,0 +1,38 @@
+name: Changelog
+
+on:
+  workflow_dispatch:
+  push:
+    paths-ignore:
+      - '**/*'
+      - '!.github/workflows/changelog.yml'
+      - '!src/**/*.csproj'
+      - '!src/**/*.cs'
+    branches:
+      - 'master' 
+
+jobs:
+  changelog:
+    if: github.ref == 'refs/heads/master' && github.repository == 'christianhelle/apiclientcodegen'
+    runs-on: ubuntu-latest
+    steps:
+      - name: 🛒 Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          token: ${{ secrets.PAT }}
+      - name: Setup Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '3.2'
+      - name: Install github_changelog_generator
+        run: gem install github_changelog_generator
+      - name: Re-generate CHANGELOG.md
+        run: github_changelog_generator --user christianhelle --project apiclientcodegen --token ${{ secrets.PAT }}
+      - name: Git commit CHANGELOG.md
+        run: |
+          git config --global user.name "Continuous Integration"
+          git config --global user.email "[email protected]"
+          git add CHANGELOG.md
+          git commit -m "Update changelog [skip ci]"
+          git push