Feature or enhancement

In Python 3.13 we added colour output to the new REPL, tracebacks and doctest, and in 3.14 to unittest, that can also be controlled with the PYTHON_COLORS, NO_COLOR and FORCE_COLOR environment variables:

• https://docs.python.org/3.14/whatsnew/3.14.html#unittest
• https://docs.python.org/3.14/using/cmdline.html#using-on-controlling-color

Let's add colour to test.regrtest output.

Linked PRs

• gh-127718: Add colour to test.regrtest output #127719