fix: assign Sequences

[cmp0xff]

Describe the bug

Following #1250, DataFrame.assign() should allow Sequences, e.g. tuples

To Reproduce

import pandas as pd
df = pd.DataFrame({"a": (1,2,3)})
df = df.assign(d=lambda df: (10,20,30))

Need to update IntoColumn in _typing.pyi to include Sequence[Scalar]

Please complete the following information

• OS: Windows 11

• python version: 3.10

• mypy 1.16.0

• version of installed pandas-stubs : development version

• Tests added: Please use assert_type() to assert the type of any return value

[Dr-Irv]

thanks @cmp0xff