Updating Python and NumPy versions

To update the minimum versions of Python we need to update:

- ``pyproject.toml`` (classifiers, requires-python, ``[ruff.tool]`` target-version)

- ``environment.yml``

- ``doc/install/dependencies.rst``

- ``doc/devel/min_dep_policy.rst`` (this file)

- CI configuration files (circle, GHA, azure)

To update the minimum NumPy we need to update:

- ``pyproject.toml``

- ``environment.yml``

- ``doc/install/dependencies.rst``

- ``doc/devel/min_dep_policy.rst`` (this file)

- ``requirements/testing/minver.txt``

- ``lib/matplotlib/__init__.py`` (matplotlib._check_versions())

The work to leverage new features or remove workarounds for no-longer supported

versions should be done in a follow-on PRs to keep the version bump PRs well

scoped.

In both cases add an api_changes/development with the following template:

.. rst::

Increase to minimum supported versions of dependencies

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

For Matplotlib 3.ZZ, the :ref:`minimum supported versions <dependencies>` are

being bumped:

+------------+-----------------+----------------+

| Dependency | min in mpl3.N | min in mpl3.M |

+============+=================+================+

| Python | 3.XX | 3.AA |

| NumPy | 1.YY | 1.BB |

+------------+-----------------+----------------+

This is consistent with our :ref:`min_deps_policy` and `SPEC0

<https://scientific-python.org/specs/spec-0000/>`__