bpo-31649: Make IDLE's _htest, _utest parameters keyword-only. (#3839)

diff --git a/Lib/idlelib/pathbrowser.py b/Lib/idlelib/pathbrowser.py
index b0c8c6d..c0aa2a1 100644
--- a/Lib/idlelib/pathbrowser.py
+++ b/Lib/idlelib/pathbrowser.py
@@ -9,7 +9,7 @@
 
 class PathBrowser(ModuleBrowser):
 
-    def __init__(self, flist, _htest=False, _utest=False):
+    def __init__(self, flist, *, _htest=False, _utest=False):
         """
         _htest - bool, change box location when running htest
         """