Replace deprecated faker.datatype.uuid() with faker.string.uuid()
The frontend tests are currently full of this warning:
[@faker-js/faker]: faker.datatype.uuid() is deprecated since v8.0 and will be removed in v9.0. Please use faker.string.uuid() instead.
(see e.g. https://dev.funkwhale.audio/funkwhale/funkwhale/-/jobs/221382)