use --codspeed flag in benchmark ci

Author: d-v-b

.github/workflows/codspeed.yml

@@ -27,4 +27,4 @@ jobs:
       uses: CodSpeedHQ/action@v4
       with:
           mode: instrumentation
-          run: hatch run test.py3.11-1.26-minimal:run-benchmark
+          run: hatch run test.py3.11-1.26-minimal:pytest tests/benchmarks --codspeed