You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.
mstplotlib was reported malicious
OSV:MAL-2025-2345 - Malicious code in mstplotlib (PyPI)

mstplotlib
3.10.2

This version was deleted from PyPI around 2025-02-21. Installing fails with:
$ pip3 install mstplotlib==3.10.2 ERROR: Could not find a version that satisfies the requirement mstplotlib==3.10.2
View other deleted versions of mstplotlib

Install through StableBuild

You can install this package from StableBuild's PyPI snapshots from before the version was deleted:
pip3 install \ -i https://YOUR_API_KEY.pypimirror.stablebuild.com/2025-02-20/ \ mstplotlib==3.10.2
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Or, download files manually

And install manually via pip:
mstplotlib-3.10.2.tar.gz (0.8KB)