fixes after change to src-layout

tests/conftest.py

@@ -0,0 +1,11 @@
+import pytest
+from typing import Any
+
+
+def pytest_addoption(parser: pytest.Parser) -> None:
+    parser.addoption("--relaxed", action='store_true', help="run tests in relaxed mode")
+
+
+@pytest.fixture
+def relaxed(request: pytest.FixtureRequest) -> Any:
+    return request.config.getoption("--relaxed")