Unblock League Gothic

[RosaWagner]

Recalibrate slant axis as ital and ship it again
cf #2325

[RosaWagner]

@davelab6 I plan to deal with that this week or next week. The PR doesn't link to the author repo, which source is the truth ?

https://github.com/theleagueof/league-gothic
or https://github.com/bghryct/league-gothic/tree/gf

[RosaWagner]

Marc says we should try to sync both repo and see with @alerque how we could organise that

[davelab6]

I posted essentially the same Q at theleagueof/league-gothic#28 (comment)

[RosaWagner]

I close this and follow up in #1212