Changes

pySim.esim.saip: Fix compatibility with pytohn < 3.11

In python up to 3.10, the byteorder argument of the int.to_bytes()
method was mandatory, even if the length of the target byte sequence
is 1 and there factually is no byteorder.

https://docs.python.org/3.10/library/stdtypes.html#int.to_bytes
vs
https://docs.python.org/3.11/library/stdtypes.html#int.to_bytes

See also: https://discourse.osmocom.org/t/assistance-required-with-saip-pysim-tool-error-while-adding-applets-to-exiting-upp-der/2413/2

Change-Id: I8ba29d42c8d7bf0a36772cc3370eff1f6afa879f