Fix settings of automated PR

.github/workflows/update_backend.yml

@@ -61,8 +61,8 @@ jobs:
       - name: "Create PR"
         if: ${{ steps.get-latest.outputs.version != steps.get-current.outputs.version }}
         uses: peter-evans/create-pull-request@v3
-        env:
-          GITHUB_TOKEN: ${{ secrets.REPO_SCOPED_TOKEN }}
+        with:
+          token: ${{ secrets.REPO_SCOPED_TOKEN }}
           title: "Automated update to backend: v${{ steps.get-latest.outputs.version }}"
           body: |
             This PR was automatically generated by the GitHub Action
@@ -71,3 +71,4 @@ jobs:
             It updates the backend version to v${{ steps.get-latest.outputs.version }}.
             For a full description of the changes, see the backend
             changelog: [v${{ steps.get-latest.outputs.version }}](https://github.com/MilesCranmer/SymbolicRegression.jl/releases/tag/v${{ steps.get-latest.outputs.version }}).
+          delete-branch: true