Replace ursa with indy_bls #1641
Description
The Ursa project is now archived.
indy_bls is soon-to-be published as a replacement for the python-ursa wrapper.
It should be possible to install the wheel package from PyPI as there is support for manylinux-2014-aarch64 and manylinux-2014-x86_64. The ursa Debian package can also be removed as a dependency.
In the Python code, from ursa.bls ... becomes from indy_bls ... and from ursa.indy_error import IndyCryptoError becomes from indy_bls import IndyBlsError.