The required version of pycryptodome currently is either 3.7.2 or 3.7.3.
But there is no wheel package for these version for latest version of python
(3.8). Due to this, pip will download source and compile while trying to
install pycryptodome. On Windows, there is no c, c++ compiler installed
by default which leads to pip asking users to download and install
Microsoft Visual C++ Build Tools.

The release version 3.9.3 contains wheel package for python 3.8 on
all supported operating systems.

Signed-off-by: Devaraj Ranganna <devaraj.ranganna@arm.com>