ImageMath.eval deprecation warning running selftest.py

[hugovk]

During the release, make release-test runs python3 selftest.py:

❯ python3 selftest.py
...
Running selftest:
<doctest __main__.testimage[57]>:1: DeprecationWarning: ImageMath.eval is deprecated and will be removed in Pillow 12 (2025-10-15). Use ImageMath.lambda_eval or ImageMath.unsafe_eval instead.
  im = ImageMath.eval("float(im + 20)", im=im.convert("L"))
--- 59 tests passed.

Here's the eval:

Pillow/selftest.py

Line 142 in 33a73b5

>>> im = ImageMath.eval("float(im + 20)", im=im.convert("L"))

Shall we rewrite it as lambda_eval, catch the deprecation warning, or just remove it?

[radarhere]

Rewriting it with lambda_eval would be my suggestion. #7960