add github release workflow

Author: navedmerchant

.github/workflows/release.yml

@@ -0,0 +1,43 @@
+name: Create GitHub release
+
+on:
+  push:
+    tags:
+      - "*"
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    name: Release tagged mainline commit
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Check out repository history
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check whether the tag is on mainline
+        id: tag-check
+        env:
+          TAG_NAME: ${{ github.ref_name }}
+        shell: bash
+        run: |
+          git fetch --no-tags origin mainline
+          tag_commit="$(git rev-list -n 1 "$TAG_NAME")"
+
+          if git merge-base --is-ancestor "$tag_commit" origin/mainline; then
+            echo "on_mainline=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "on_mainline=false" >> "$GITHUB_OUTPUT"
+            echo "Tag $TAG_NAME does not point to a commit on mainline; skipping release."
+          fi
+
+      - name: Create GitHub release
+        if: steps.tag-check.outputs.on_mainline == 'true'
+        env:
+          GH_TOKEN: ${{ github.token }}
+          TAG_NAME: ${{ github.ref_name }}
+        run: gh release create "$TAG_NAME" --verify-tag --generate-notes --title "$TAG_NAME"