Corrected passenv value for tox 4.0.6+.

tox.ini

@@ -20,7 +20,7 @@ basepython = python3
 [testenv]
 usedevelop = true
 # OBJC_DISABLE_INITIALIZE_FORK_SAFETY fixes hung tests for MacOS users. (#30806)
-passenv = DJANGO_SETTINGS_MODULE PYTHONPATH HOME DISPLAY OBJC_DISABLE_INITIALIZE_FORK_SAFETY
+passenv = DJANGO_SETTINGS_MODULE,PYTHONPATH,HOME,DISPLAY,OBJC_DISABLE_INITIALIZE_FORK_SAFETY
 setenv =
     PYTHONDONTWRITEBYTECODE=1
 deps =