refactor(test) test.py -> test/__init__.py

Author: tony

src/libtmux/test.py renamed to src/libtmux/test/__init__.py

@@ -10,7 +10,7 @@
 import time
 import typing as t
 
-from .exc import WaitTimeout
+from libtmux.exc import WaitTimeout
 
 logger = logging.getLogger(__name__)