fix workflow

Author: mulle-nat

.github/workflows/release.yml

@@ -23,11 +23,7 @@ jobs:
       run: make
 
     - name: Upload Release Asset
-      uses: actions/upload-release-asset@v1
-      env:
-        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      uses: softprops/action-gh-release@v1
+      if: startsWith(github.ref, 'refs/tags/')
       with:
-        upload_url: ${{ github.event.release.upload_url }}
-        asset_path: ./mulle-todo
-        asset_name: mulle-todo
-        asset_content_type: application/octet-stream
+        files: mulle-todo