build/pkgs/matplotlib 3.9.2, contourpy 1.2.1

[mkoeppe]

Split out from #38227

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

⌛ Dependencies

• Depends on build/pkgs/numpy 2.0.1, scipy 1.13.1, cmake 3.30.2, gsl 2.8, meson 1.5.1, meson_python 0.16.0, ninja_build 1.12.1, openblas 0.3.28, pybind11 2.13.1, pythran 0.16.1 #38227

[mkoeppe]

Open: #38227 (comment)

[github-actions]

Documentation preview for this PR (built with commit 7c6a649; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[orlitzky]

This is obsolete now, we're past these versions:

$ cat build/pkgs/matplotlib/package-version.txt
3.10.1
$ cat build/pkgs/contourpy/package-version.txt 
1.3.1