message: Update quickcheck to 0.7
diff: @@ -20,7 +20,7 @@ thread-scoped = "1.0.2"
  [dev-dependencies]
  approx = "0.1.1"
  itertools-num = "0.1"
  -quickcheck = { version = "0.6", default-features = false }
  +quickcheck = { version = "0.7", default-features = false }
  criterion = { path="..", version="0.2.1", default-features = false }
  [badges]
  