gh-36765: Update to new conway-polynomials python package
Fix https://github.com/sagemath/sage/issues/32747 by switching to the
newly-minted [conway-polynomials
package](https://pypi.org/project/conway-polynomials/0.7/) on pypi.
IMO `sage.databases.conway` (which makes the dict immutable by wrapping
it in a class) is of dubious value but I've left everything alone for
now.
URL: https://github.com/sagemath/sage/pull/36765
Reported by: Michael Orlitzky
Reviewer(s): François Bissey, Matthias Köppe, Michael Orlitzky, Tobias Diez
