Bump aeson bound to < 1.6

Author: lukel97

stylish-haskell.cabal

@@ -138,7 +138,7 @@ Test-suite stylish-haskell-tests
     test-framework-hunit >= 0.2 && < 0.4,
     random               >= 1.1,
     -- Copied from regular dependencies...
-    aeson            >= 0.6    && < 1.5,
+    aeson            >= 0.6    && < 1.6,
     base             >= 4.8    && < 5,
     bytestring       >= 0.9    && < 0.11,
     Cabal            >= 2.4    && < 3.1,