Incorrect type of dependency_groups?

[zedzhen]

dependency_groups: Mapping[str, str | Mapping[str, str]], but i think correct type is Mapping[str, list[str | Mapping[str, str]]] (value is list).

dependency-groups/src/dependency_groups/_implementation.py

Lines 132 to 134 in 2da01b1

	def _parse_group(
	self, group: str
	) -> tuple[Requirement | DependencyGroupInclude, ...]:

group is str

dependency-groups/src/dependency_groups/_implementation.py

Lines 142 to 144 in 2da01b1

	raw_group = self.dependency_groups[group]
	if not isinstance(raw_group, list):
	raise TypeError(f"Dependency group '{group}' is not a list")

raw_group is a value of dependency_groups => is str | Mapping[str, str]
but check is list

and in exmaple

[dependency-groups]
test = ["pytest", {include-group = "runtime"}]
runtime = ["flask"]

type of value of dependency-groups is list