doc: pytest: Complete dependencies list with missing packages

doc: pytest: Complete dependencies list with missing packages

Add missing dependencies to the pytest usage documentation and correct
the device tree compiler package name from 'dtc' to 'device-tree-compiler'.

This ensures users have the complete list of dependencies needed to run
the pytest test suite without errors.

Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>