Deprecated `pvsystem.sapm_spectral_loss` not removed

[RDaxini]

Describe the bug
pvsystem.sapm_spectral_loss was deprecated since v10.0 but I could not find any PRs to remove it in a future version (12.0?)

To Reproduce
Steps to reproduce the behavior:
See the read the docs page
and the tests

Expected behavior
Removed in v11.0

Versions:

• pvlib.__version__: 11.2

Additional context
I am not super familiar with deprecations so please correct me if I have misunderstood something here or even missed an existing PR for this...

[kandersolar]

Yes, removing functions is done in .0 releases, so this will wait until 0.12.0 at the earliest. It's okay to leave #2244 open in the meantime, but opening PRs "early" like that means you may have to resolve some merge conflicts between now and then :)