In the sign app, if a signature is saved in mobile resolution, when the user tries to sign a document in desktop, the size that is shown is the mobile size, which is strange for the user.
This PR is an odoo change and it modifies the library method that adds the image to the canvas, resizing the image to the canvas size.
task-2479787
closesodoo/odoo#68160
Signed-off-by: Arnaud Joset <arj-odoo@users.noreply.github.com>