typing.Literal isn't supported properly on Python 3.9.0

[Fatal1ty]

• mashumaro version: 3.7
• Python version: 3.9.0
• Operating System: macOS 13.2.1

Description

Function is_literal doesn't return True for typing.Literal[42] on Python 3.9.0. Type of typing.Literal instances has been changed from _GenericAlias to _LiteralGenericAlias since 3.9.1.

• [3.9] bpo-42345: Fix three issues with typing.Literal parameters (GH-23294) python/cpython#23335

[Fatal1ty]

We should add or PY_39 to the first condition and replace PY_39_MIN with PY_310_MIN here:

mashumaro/mashumaro/core/meta/helpers.py

Lines 364 to 373 in a89a673

	def is_literal(typ: Type) -> bool:
	if PY_37 or PY_38:
	with suppress(AttributeError):
	return is_generic(typ) and get_generic_name(typ, True) == "Literal"
	elif PY_39_MIN:
	with suppress(AttributeError):
	# noinspection PyProtectedMember
	# noinspection PyUnresolvedReferences
	return type(typ) is typing._LiteralGenericAlias # type: ignore
	return False