chore: move python version compatibility to 3.10

[cmatsuoka]

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[cmatsuoka]

Rebased on features/2.0

[mr-cal]

Looks good, a few non-blocking thoughts:

1. Can you use from collections import namedtuple instead of from typing import NamedTuple?
2. There's a leftover Optional here:

   craft-parts/craft_parts/overlays/layers.py

   Line 45 in 78bbc6a

   cls, part: Part, *, previous_layer_hash: Optional["LayerHash"]

3. There's a leftover Union here:

   craft-parts/craft_parts/packages/apt_cache.py

   Line 395 in 78bbc6a

   path: Union[str, "os.PathLike[str]"], names: Iterable[str]

[lengau]

Re: @mr-cal 's #1: I don't like the location of typing.NamedTuple, but it's better to use when we're using strong typing. Ideally we'd replace most or all of these with dataclasses in a separate PR.

[lengau]

LGTM! The one thing I caught doesn't really need changing because it goes away with pydantic 2 anyway.

[lengau]

GitHub's not letting me apply the suggestion to the full thing, but:

Suggested change

	if TYPE_CHECKING:
	UniqueStrList Annotated[liststr], conlist(str, unique_items=True)]

[cmatsuoka]

Removed remaining Optional and Union instances, typing adjustments to be handled separately.