[mypy] Add type annotations for linked queue in data structures

[dylanbuchi]

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[cclauss]

Adding from __future__ import annotations as the first line of code should enable the more readable syntax.

Suggested change

	self.next: Optional[Node] = None
	self.next: Node | None = None

https://docs.python.org/3/library/typing.html#typing.Optional

[cclauss]

LGTM

[cclauss]

In general, I tend to use type hints for function parameters and return types where they are most valuable in finding bugs but there is nothing wrong with this usage. I find that sometimes overuse of type hints slows down those who are reading the code.