fix: add py.typed marker (#1350)

# Description
I noticed that our mypy evaluation was failing upon importing
`deltalake` package due to missing `py.typed` marker or a stubs package.
Given there is type information already annotated in this repo, it makes
sense for the python package to be
[PEP-561](https://peps.python.org/pep-0561/#packaging-type-information)
compatible.

Maturin should pick this file up and distribute it correctly, according
to [the
documentation](https://www.maturin.rs/project_layout.html?highlight=py.typ#adding-python-type-information)

# Related Issue(s)
No open issues (I could find)

# Documentation
https://peps.python.org/pep-0561/#packaging-type-information

https://www.maturin.rs/project_layout.html?highlight=py.typ#adding-python-type-information