Remove redundant constraints from cabal.project

`cabal-doctest` has now been fixed

Author: neilmayhew

cabal.project

@@ -36,9 +36,6 @@ if os(windows)
   constraints: time ^>=1.14
   allow-newer: *:time
 
--- Temporary workaround for problem with cabal-doctest
-constraints: Cabal <3.14
-
 -- Depending on C++ for just so slightly faster utf8 parsing is a bit annoying
 -- especially as it brings in all kinds of complications for GHC.
 package text