feat: add c2corg/browserslist-update-action (#313)

* feat: add c2corg/browserslist-update-action
* chore: update wording, vars, add workflow_dispatch

.github/workflows/update-browserslist.yaml

@@ -0,0 +1,37 @@
+---
+name: Update Browserslist database
+
+on:
+  schedule:
+    # At 02:00 on day-of-month 1 and 15.
+    - cron: '0 2 1,15 * *'
+  workflow_dispatch:
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  update-browserslist-database:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Configure git
+        run: |
+          git config user.name "fiximus"
+          git config user.email "189535814+fiximus@users.noreply.github.com"
+      - name: Update Browserslist database and create PR if applies
+        uses: c2corg/browserslist-update-action@v2
+        with:
+          directory: ./packages/browserslist-config/
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          branch: ${{ vars.BROWSERSLIST_UPDATE_BRANCH || 'browserslist-update' }}
+          base_branch: ${{ vars.DEFAULT_BRANCH || 'main' }}
+          commit_message: 'chore(deps): update browserslist database'
+          title: 'chore(deps): update browserslist database'
+          body: Auto-generated by [browserslist-update-action](https://github.com/c2corg/browserslist-update-action/)
+          labels: 'maintenance'
+          reviewers: 'ivuorinen'