[BUG]: missing changelog for 3.1.0 on readthedocs

[bmerry]

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What version (or hash if on master) of pybind11 are you using?

3.1.0

Problem description

https://pybind11.readthedocs.io/en/stable/changelog.html stops at 3.0.4 and is missing 3.1.0.

Reproducible example code

Is this a regression? Put the last known working version here if it is.

Not a regression