Adding in FAR clause

[vdavez]

See Issue #1.

Current functionality includes:

from procurement_tools.far import FAR
section = FAR.get_section("17.502-2")
# `section` is now a pydantic model
print(section.model_dump())
# Returns a dict with the title, section number, url, and text of the section

# subpart = FAR.get_subpart("17.5")
print(subpart.model_dump())
# Returns a dict with the title, subpart number, url, and a list of sections in the subpart