Bug 17175: Typo in patron card images error message

Bug 17175: Typo in patron card images error message

To test:
1) Go to Tools -> Patron Card Creator -> New Image
2) Click Upload without attaching anything
3) Notice typo
4) Apply patch and refresh page (resend information if prompted)
5) Notice typo fixed

Sponsored-by: Catalyst IT
Signed-off-by: Claire Gravely <claire_gravely@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit ea13ea00830a8061842fa13b6110e0a4e75aa444)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
(cherry picked from commit 2279c2b64e1c26c5221d92727e3f4d7c0bfe1b9a)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>