compose.Select fix type annotation

[tauferp]

Versions

river version: 0.21.0
Python version: 3.12.4
Operating system: Ubuntu 24

Describe the bug

compose.Select init method has weird/likely wrong type annotations:

    def __init__(self, *keys: tuple[base.typing.FeatureName]):

This makes it seem like every key should be a tuple, when the real use case looks more like:

    def __init__(self, *keys: base.typing.FeatureName):

Steps/code to reproduce

Using example from https://riverml.xyz/dev/api/compose/Select/#examples

from river import compose

x = {'a': 42, 'b': 12, 'c': 13}
compose.Select('c').transform_one(x)

Running current mypy 1.15.0 yeilds:

$ mypy sample.py 
sample.py:4: error: Call to untyped function "transform_one" in typed context  [no-untyped-call]
sample.py:4: error: Argument 1 to "Select" has incompatible type "str"; expected "tuple[Hashable]"  [arg-type]
Found 2 errors in 1 file (checked 1 source file)

Where using the proposed annotations yields:

$ mypy sample.py 
sample.py:4: error: Call to untyped function "transform_one" in typed context  [no-untyped-call]
Found 1 error in 1 file (checked 1 source file)