Bug 27203: Adjust unit tests

Bug 27203: Adjust unit tests

It seems the issue here is that the price passed in is a string, and not a number, so the tax
value is not calculated when no unitprice is provided

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit e5d42896b8076e24c6948009d7552b6cdba964f0)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit 6eb3790ff489bd9a012960d5abdd5d1fe6e2b20d)

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>