chore(common): Move version to libtmux's backport

Author: tony

src/tmuxp/plugin.py

@@ -1,6 +1,5 @@
-from packaging.version import Version
-
 import libtmux
+from libtmux._compat import LegacyVersion as Version
 from libtmux.common import get_version
 
 from .__about__ import __version__