profiles ask for Twitter handle rather than X

[StephDriver]

profiles still ask for Twitter handle, but main pages have been updated to X.

https://www.openlibhums.org/profile/

[joemull]

@StephDriver this comes from a model definition in core Janeway:

https://github.com/BirkbeckCTP/janeway/blob/a0a87f5cc99c5fe2fb43c21af1f3c55b324b9ae6/src/core/models.py#L253

But rather than change just this one field I think we should implement a generic social media link field.

[joemull]

Blocked until Janeway can flexibly handle different social media links and labels.