Unconstrain cassava per commercialhaskell/stack#3345

Author: DanBurton

build-constraints.yaml

@@ -3064,9 +3064,6 @@ packages:
         # https://github.com/fpco/stackage/issues/2740
         - fgl < 5.6
 
-        # https://github.com/commercialhaskell/stack/issues/3345
-        - cassava < 0.5.1.0
-
         # https://github.com/fpco/stackage/issues/3044
         - either < 4.5 # Latest ATOW is either-5
         - rebase < 1.2