Exclude test for old GHC

Author: Dan Fithian

tests/UnitTests.hs

@@ -344,10 +344,10 @@ fromJSONKeyAssertions =
     [ assertIsCoerce  "Text"            (fromJSONKey :: FromJSONKeyFunction Text)
     , assertIsCoerce  "Tagged Int Text" (fromJSONKey :: FromJSONKeyFunction (Tagged Int Text))
     , assertIsCoerce  "MyText"          (fromJSONKey :: FromJSONKeyFunction MyText)
-    , assertIsCoerce  "Const Text"      (fromJSONKey :: FromJSONKeyFunction (Const Text ()))
 
 #if __GLASGOW_HASKELL__ >= 710
     , assertIsCoerce' "MyText'"         (fromJSONKey :: FromJSONKeyFunction MyText')
+    , assertIsCoerce  "Const Text"      (fromJSONKey :: FromJSONKeyFunction (Const Text ()))
 #endif
     ]
   where