Add neovim 0.6 to run-tests (#3998)

* Update test scripts
* Remove neovim 0.3 and 0.4
* Add neovim 0.6.1

Co-authored-by: Horacio Sanson <horacio@allm.inc>
Co-authored-by: w0rp <devw0rp@gmail.com>

test/test_set_list_timers.vader

@@ -26,4 +26,4 @@ Execute(The SetLists function should work when run in a timer):
   \ 'nr': 0,
   \ 'type': 'E',
   \ 'pattern': '',
-  \}], ale#test#GetLoclistWithoutModule()
+  \}], ale#test#GetLoclistWithoutNewerKeys()