unpin setuptools

unpin setuptools

This removes the pin that was placed in 2607262110bdc5c5dc96fc19ddca895a15a58e4e

The pin for ``setuptools<69.3`` in ``pyproject.toml`` has been
removed.  This pin was to prevent a sudden change to :pep:`625` in
setuptools from taking place which changes the file name of SQLAlchemy's
source distribution on pypi to be an all lower case name, which is very
likely to cause problems with various build environments that expected a
particular naming style.  However, the presence of this pin is now holding
back environments that otherwise want to use a newer setuptools, so we've
decided to move forward with this change, with the assumption that build
environments will have largely accommodated the setuptools change by
now.

References: #11818
Change-Id: I0cd9ab0512004669a8f0aa0cb7f560d89a2da2bd