Allow lens-aeson 1.2 (#27)

Fixes #26

Author: maksbotan

servant-openapi3.cabal

@@ -118,7 +118,7 @@ test-suite spec
                   , hspec >=2.6.0 && <2.10
                   , QuickCheck
                   , lens
-                  , lens-aeson >=1.0.2    && <1.2
+                  , lens-aeson >=1.0.2    && <1.3
                   , servant
                   , servant-openapi3
                     -- openapi3 3.1.0 fixes some ordering-related issues, making tests stable