Refactor path addition to sys.path in conftest.py

CI: package install + path safety; use Python 3.11

Author: sensor-aae

tests/conftest.py

@@ -1,7 +1,6 @@
 import sys
 from pathlib import Path
-
-# Add the repo root to sys.path so "import risk_engine" works in CI
 ROOT = Path(__file__).resolve().parents[1]
-if str(ROOT) not in sys.path:
-    sys.path.insert(0, str(ROOT))
+p = str(ROOT)
+if p not in sys.path:
+    sys.path.insert(0, p)