fixup! feat(Session.new_window): set up environment

Author: zappolowski

tests/test_session.py

@@ -1,5 +1,6 @@
 """Test for libtmux Session object."""
 import logging
+import shutil
 import typing as t
 
 import pytest
@@ -260,10 +261,13 @@ def test_cmd_inserts_sesion_id(session: Session) -> None:
 
 
 def test_new_window_with_environment(session: Session) -> None:
+    env = shutil.which("env")
+    assert env is not None, "Cannot find usable `env` in PATH."
+
     window = session.new_window(
         attach=True,
         window_name="window_with_environment",
-        window_shell="/usr/bin/env PS1='$ ' bash --norc --noprofile",
+        window_shell=f"{env} PS1='$ ' bash --norc --noprofile",
         environment={"ENV_VAR": "window"},
     )
     pane = window.attached_pane