ci: remove dist loadscope from workflow testing

Author: harryswift01

.github/workflows/pr.yaml

@@ -106,13 +106,12 @@ jobs:
           python -m pip install --upgrade pip
           python -m pip install -e .[testing]
 
-      - name: Run fast regression tests (parallel)
+      - name: Run fast regression tests (sequential for determinism)
         run: |
           python -m pytest tests/regression \
             -m "not slow" \
             -k "${{ matrix.system }}" \
             -n 0 \
-            --dist=loadscope \
             -vv \
             --durations=20