test: add conftest to ensure src is importable in CI

Author: andrepsousa

tests/conftest.py

@@ -0,0 +1,6 @@
+import os
+import sys
+
+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)