Reference base properly

Author: simonswine

.github/workflows/pyrobench.yaml

@@ -24,6 +24,6 @@ jobs:
 
     - name: Run Benchmark
       run: |
-        go run github.com/grafana/pyrobench@26f65feff9ff5ad092fb21b6931be8b730554a86 -v compare --git-base $GITHUB_BASE_REF --github-commenter
+        go run github.com/grafana/pyrobench@26f65feff9ff5ad092fb21b6931be8b730554a86 -v compare --git-base origin/$GITHUB_BASE_REF --github-commenter
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}