"ERROR: Unknown Unsplash URL!" is generated when we try to add premium Unsplash images. This is because when we add the unsplash image, it accepts the image whose URL starts with "https://images.unsplash.com/" but the premium image URL starts with "https://plus.unsplash.com/". This commit solves the above issue by checking that the premium splash image link starts with the correct format. sentry-4075507166 closes odoo/odoo#118662 X-original-commit: 00894718cc7332131a7096c1e6dbe124d5d6d233 Signed-off-by: Romain Derie (rde) <rde@odoo.com>