Upgrade to Cython 3.0.0, use embedsignature=True

adding pyproject.toml

Fix polars columns= deprecation for schema=

Add a note about how TA-Lib handles NaN's.

update changelog

remove pyproject.toml which may be preventing some installs.

Regenerate _ta_lib.c.

Fixed {MIN/MAX/MINMAX}INDEX functions to return correct indices.

Update to 0.4.20.

README: formatting.