Remove the @phpstan-ignore annotation in the MailboxEmail factory

[marien-probesys]

Problem

Foundry 2.2.2 doesn't correctly type the instantiator parameter of instantiateWith. See zenstruck/foundry#721.
As this is not an important issue, I preferred to update Foundry and add the annotation to ignore the issue.

Solution

Update Foundry and remove the annotation and the related comment in \App\Tests\Factory\MailboxEmailFactory.