Fix errors when publishing to GoToSocial

GoToSocial is fully Mastodon-compatible, so Typefully should be able to support it, but there's currently a gotcha. You can connect a GTS account as a Mastodon account (like you can on most services that support Mastodon) and posts will publish, but it generates an error like this:

Field 'mastodonpostpublishedtootsids' expected a number but got '01KE7V22A03NFSS37T8E6TT42V'.

ActivityPub doesn't mandate numeric IDs, but because Mastodon always generates numeric ones, it looks like your system is assuming they will always be numeric and thinks something went wrong because it's alphanumeric. If you drop this requirement, you'll likely be able to support GoToSocial without any other changes.