Allow aeson-2.1

Author: andreasabel

github.cabal

@@ -179,7 +179,7 @@ library
 
   -- other packages
   build-depends:
-      aeson                 >=1.4.0.0    && <1.6 || >=2.0.1.0 && <2.1
+      aeson                 >=1.4.0.0    && <1.6 || >=2.0.1.0 && <2.2
     , base-compat           >=0.11.1     && <0.13
     , base16-bytestring     >=0.1.1.6    && <1.1
     , binary-instances      >=1          && <1.1