src/meta-openembedded:python3-rsa: Upgrade 3.4.2 -> 4.6

Upgrade to release 4.6:

- Rolled back the switch to Poetry, and reverted back to using
  Pipenv + setup.py for dependency management. There apparently
  is an issue no-binary installs of packages build with Poetry.
- Limited SHA3 support to those Python versions (3.6+) that
  support it natively. The third-party library that adds support
  for this to Python 3.5 is a binary package, and thus breaks the
  pure-Python nature of Python-RSA.
- To avoid older Python installations from trying to upgrade to
  RSA 4.4, this is now made explicit in the python_requires
  argument in setup.py

The encrypt/decrypt-bigfile CLI commands have been removed in
2016 therefore the recipe has been updated accordingly.

Signed-off-by: Leon Anavi <[email protected]>
Signed-off-by: Khem Raj <[email protected]>
Acked-by: Trevor Gamblin <[email protected]>

Author: leon-anavi