test: add conftest to ensure src is importable in CI

Author: andrepsousa

tests/conftest.py

@@ -3,4 +3,4 @@
 
 PROJECT_ROOT = os.path.abspath(os.path.join(os.path.dirname(_file_), ".."))
 if PROJECT_ROOT not in sys.path:
-    sys.path.insert(0, PROJECT_ROOT)
+    sys.path.insert(0, PROJECT_ROOT)