Update yarl to 1.21.0

[pyup-bot]

This PR updates yarl from 1.20.1 to 1.21.0.

Changelog

1.21.0

======

*(2025-10-05)*


Contributor-facing changes
--------------------------

- The :file:`reusable-cibuildwheel.yml` workflow has been refactored to
be more generic and :file:`ci-cd.yml` now holds all the configuration
toggles -- by :user:`webknjaz`.

*Related issues and pull requests on GitHub:*
:issue:`1535`.

- When building wheels, the source distribution is now passed directly
to the ``cibuildwheel`` invocation -- by :user:`webknjaz`.

*Related issues and pull requests on GitHub:*
:issue:`1536`.

- Added CI for Python 3.14 -- by :user:`kumaraditya303`.

*Related issues and pull requests on GitHub:*
:issue:`1560`.


----

Links

• PyPI: https://pypi.org/project/yarl
• Changelog: https://data.safetycli.com/changelogs/yarl/
• Repo: https://github.com/aio-libs/yarl

[pyup-bot]

Closing this in favor of #1055