Add pyupgrade as a pre-commit hook

[kurtmckee]

This introduces pyupgrade as a pre-commit hook, then runs pre-commit run -a and commits the changes introduced.

The changes involve one of these two categories of changes:

• typing.X is a deprecated alias for collections.abc.X
• Type annotations no longer require Dict/List/etc, and can be replaced with dict/list/etc.

[Copilot]

Pull Request Overview

This PR introduces pyupgrade as a pre-commit hook to modernize Python code by automatically converting deprecated typing aliases to their current equivalents. The changes update type annotations to use built-in types (dict, list) instead of typing module equivalents (Dict, List) and move Container and Iterator from typing to collections.abc.

• Adds pyupgrade (v3.20.0) configured for Python 3.9+ to pre-commit hooks
• Converts deprecated typing aliases to modern equivalents across the codebase
• Updates CHANGELOG.rst to document this development improvement

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
.pre-commit-config.yaml	Adds pyupgrade hook with Python 3.9+ configuration
jwt/types.py	Removes Dict import and uses dict for type annotation
jwt/jwks_client.py	Converts Optional[T] to T | None, Dict to dict, List to list
jwt/help.py	Removes Dict import and uses dict for nested type annotations
jwt/api_jwt.py	Moves Container from typing to collections.abc
jwt/api_jwk.py	Moves Iterator from typing to collections.abc
CHANGELOG.rst	Documents the addition of pyupgrade pre-commit hook

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[kurtmckee]

Rebased on master and resolved merge conflicts.