yarl 1.21.0

on Python PyPI

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:
  #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:
  #1536.

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

  Related issues and pull requests on GitHub:
  #1560.