OrderedDict import is no longer needed (#4890)

OrderedDict import is no longer needed (#4890) · python/cpython@05565ed

Original file line number	Diff line number	Diff line change
`@@ -83,7 +83,6 @@`
`83`	`83`	`]`
`84`	`84`
`85`	`85`
`86`		`-import collections as _collections`
`87`	`86`	`import os as _os`
`88`	`87`	`import re as _re`
`89`	`88`	`import sys as _sys`
`@@ -1084,7 +1083,7 @@ def __init__(self,`
`1084`	`1083`
`1085`	`1084`	`self._prog_prefix = prog`
`1086`	`1085`	`self._parser_class = parser_class`
`1087`		`-self._name_parser_map = _collections.OrderedDict()`
	`1086`	`+self._name_parser_map = {}`
`1088`	`1087`	`self._choices_actions = []`
`1089`	`1088`
`1090`	`1089`	`super(_SubParsersAction, self).__init__(`