cabal outdated check before release

[endgame]

No description provided.

[endgame]

In particular, make sure we support aeson-2.0.0.0

[brendanhay]

From aeson-2.0.1.0 onward, ordered Map is the default so we should consider having the generator emit Map fields instead of HashMap - if for no other reason than to minimise Map -> HashMap conversions, but it also just seems like a more sensible default given potentially untrusted inputs / hash flooding.

See: haskell/aeson#864

[endgame]

I wonder if we should aim for aeson < 1.6 for amazonka-2.0 and then aeson >= 2.0 && < 2.1 for amazonka-2.1? We'll be asking a lot of our downstream users for the 2.0 release, as there's all the other breaking changes from the existing improvements on develop.