ci: bump CodSpeedHQ/action to v5 (#1)

v5.0.0 is out, and this workflow is what readers copy from.

Refs COD-3244

Co-authored-by: Claude <noreply@anthropic.com>

Author: adriencaccia

.github/workflows/codspeed.yml

@@ -35,7 +35,7 @@ jobs:
           make -j$(nproc)
 
       - name: Run benchmarks
-        uses: CodSpeedHQ/action@v4
+        uses: CodSpeedHQ/action@v5
         with:
           mode: walltime
           run: ./build/particle_simulation_bench