What module is this in that you want to change?

Note 1: hashlib checks upper and lower case versions of names.
So this seems like reasonable request.

Note 2: I would start hashlib.__get_builtin_constructor(name):
with 'name = name.lower()'
and replace first two 'name in' constructions with 'name =='
and shrink 2nd two lists.

Note 3. I would do same with get_algorithm_impls():
   algorithm = algorithm.lower()
Instead of possibly calling .lower twice.