Adds test execution entrypoint

Adds a main entry point to the tests directory,
allowing for test execution via `pytest.main()`.
This simplifies the process of running tests directly from the tests folder.

tests/__main__.py

@@ -0,0 +1,5 @@
+# main entry point into the test folder tests runned under pytest
+import pytest
+
+if __name__ == "__main__":
+    pytest.main()