Add HsYAML-aeson to build-depends

pandoc.cabal

@@ -417,6 +417,7 @@ library
                  case-insensitive >= 1.2 && < 1.3,
                  unicode-transforms >= 0.3 && < 0.4,
                  HsYAML >= 0.2 && < 0.3,
+                 HsYAML-aeson >= 0.2 && < 0.3,
                  doclayout >= 0.1 && < 0.2,
                  ipynb >= 0.1 && < 0.2,
                  attoparsec >= 0.12 && < 0.14