Fix importing Markup from flask

[lucaswerkmeister]

• fixes Cannot import Markup from flask #5084

I am not done with the checklist yet, will follow up immediately. But the fix is also very trivial, so I figured I’d submit it first and let you take a look already?

Checklist:

• Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• Add or update relevant docs, in the docs folder and in code. – N/A, imho
• Add an entry in CHANGES.rst summarizing the change and linking to the issue.
• Add .. versionchanged:: entries in any relevant code docs. – N/A, imho
• Run pre-commit hooks and fix any issues.
• Run pytest and tox, no tests failed.

[lucaswerkmeister]

Not sure if the checklist entry about adding tests applies? I can’t find any existing tests for deprecation warnings (git grep -i deprec tests/).

[davidism]

This is fine, thanks for catching and fixing it.

[davidism]

Flask 2.3.1 is now available on PyPI.