British media seem to be reporting that it is, but Wilder's camp say nothing is sorted yet due to Wilder's arrest.
State courts in America generally don't allow alleged felons that have been released on bond to travel outside of the US. When the alleged perpreatrator has the financial and other means to "take flight", as they say, passports are customarily required to be surrendered to the applicable criminal court. My understanding is that Wilder's next hearing is docketed for July. So, absent the charges being rescinded, it's difficult to see how the fight comes off.
if you look at wilders twitter, he apologizes to british fans, meaning he will not come to UK, fight wont happen.