Add workflow to bump version on merge to master

.github/workflows/bump-version-on-merge.yml

@@ -0,0 +1,33 @@
+name: Bump version on merge
+
+on:
+  push:
+    branches:
+      - master
+
+permissions:
+  contents: write
+
+jobs:
+  bump-version:
+    name: Bump version in config
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+        with:
+          ref: master
+          fetch-tags: true
+
+      - name: Update version in config
+        run: |
+          version="$(git describe --tags --abbrev=0)-$(git rev-parse --abbrev-ref HEAD)-$(date -u -Iseconds)"
+          sed -i "s/GRUB_BTRFS_VERSION=.*/GRUB_BTRFS_VERSION=${version}/" config
+
+      - name: Commit updated config
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add config
+          git commit -m "chore: bump version to ${version}"
+          git push origin master