I used both WAVE (Web Accessibility Evaluation Tool) and the CSS Overview panel in Chrome DevTools to identify these by checking https://python.github.io/peps/pep-0008/.

https://wave.webaim.org/report#/https://python.github.io/peps/pep-0008/

https://developer.chrome.com/blog/new-in-devtools-87/#css-overview

Some of the colours already met AA (all but one of these are for Native):

But I've bumped them all to AAA using Chrome's suggestions. They provide two suggestions, one to meet AA (4.5:1) and another for AAA (7:1).

For example, inspect element:

Click the colour box:

And click the icon to the right of the 🚫 to select AAA:

Demo

Before: https://python.github.io/peps/pep-0008/#other-recommendations
After: https://hugovk.github.io/peps/pep-0008/#other-recommendations

Before, 137 contrast errors: https://wave.webaim.org/report#/https://python.github.io/peps/pep-0008/
After, no contrast errors: https://wave.webaim.org/report#/https://hugovk.github.io/peps/pep-0008/