Resealed the Proof trait following the fix of the compiler bug causing #190
This required upgrading to Scala >= 3.4.1
Upgraded to 3.4.2
There were a few minor syntax changes that had to be propagated due to deprecations, most of this was done automatically with -rewrite -source 3.4-migration
SBT build cross versions are now set dynamically instead of as static strings.
Prooftrait following the fix of the compiler bug causing #190-rewrite -source 3.4-migration