Apply missing update for stack-9.0.1.yaml (#2556)

Author: Ailrun

stack-9.0.1.yaml

@@ -76,7 +76,6 @@ flags:
     pedantic: true
 
     ignore-plugins-ghc-bounds: true
-    class: false
     tactic: false # Dependencies fail
     stylishHaskell: false
     brittany: false