So for some weird historical reasons, the same python module is
available as pycryptodome (Crypto.* namespace) and pycryptodomex
(Cryptodome.* namespace). See the following information on the project
homepage: https://www.pycryptodome.org/src/installation
To make things extra-weird, Debian choose to package pycryptodomex as
python3-pycryptodome
(https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=886291).
So in order to support both Debian-packaged and differently-installed
packages, let's switch to pycryotodomex on all platforms/installers.
Change-Id: I04daed01f51f9702595ef9f9e0d7fcdf1e4adb62