Create update-version-file.yml

When creating a new tag (=release), this action should write the version number into the file `ada/etc/ada-version`.

Author: onnozweers

.github/workflows/update-version-file.yml

@@ -0,0 +1,30 @@
+name: Sync ada-version file
+
+on:
+  push:
+    tags:
+      - 'v*'   # run only when a version tag is pushed (like v1.2.3)
+
+jobs:
+  update-version:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Extract tag
+        run: echo "VERSION=${GITHUB_REF_NAME}" >> $GITHUB_ENV
+
+      - name: Write ada-version file
+        run: |
+          mkdir -p ada/etc
+          echo "${VERSION}" > ada/etc/ada-version
+
+      - name: Commit and push ada-version
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add ada/etc/ada-version
+          git commit -m "Update ada-version to ${VERSION}" || echo "No changes"
+          git push