Make annotation for methods more permissive

[jonathanberthias]

Summary

The type annotation for methods in the Route constructor restricts the input to lists of strings when it can accept any iterable. The methods on the Route itself are stored as a set.

I had the issue when I was trying to build new routes from other preexisting routes:

new_route = Route(
    route.path.replace("/prefix1", "/prefix2"),
    route.endpoint,
    methods=route.methods,  # type error: Argument "methods" to "Route" has incompatible type "set[str] | None"; expected "list[str] | None"
    name=f"new_{route.name}",
)

I changed the annotation to Collection, though the current implementation would work with any Iterable. Collection allows lists, sets, tuples, and Iterable would also allow generators. Let me know what you prefer.

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[alex-oleshkevich]

We typically use typing.Sequence across the project.

[jonathanberthias]

Indeed, but in this case it makes sense to allow sets in addition to list and tuples

[alv2017]

Reminder: https://docs.python.org/3/library/typing.html#deprecated-aliases
Shouldn't we start applying new standards?

[jonathanberthias]

I followed the current convention of importing everything from the typing module, but if #2867 gets merged before this PR, then I'll adjust 😄