Support aeson-2.*

[peterbecich]

When Aeson is pinned to version 2,
aeson ==2.*,
there is a compilation error:

 % cabal build all --enable-tests
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: odd-jobs-0.2.2 (user goal)
[__1] trying: servant-static-th-1.0.0.0 (dependency of odd-jobs)
[__2] trying: servant-server-0.18.3 (dependency of odd-jobs)
[__3] next goal: aeson (dependency of odd-jobs)
[__3] rejecting: aeson-2.0.2.0 (conflict: servant-server => aeson>=1.4.1.0 &&
<1.6)
[__3] skipping: aeson-2.0.1.0, aeson-2.0.0.0 (has the same characteristics
that caused the previous version to fail: excluded by constraint '>=1.4.1.0 &&
<1.6' from 'servant-server')
[__3] rejecting: aeson-1.5.6.0 (conflict: odd-jobs => aeson>=2 && <3)
[__3] skipping: aeson-1.5.5.1, aeson-1.5.5.0, aeson-1.5.4.1, aeson-1.5.4.0,
aeson-1.5.3.0, aeson-1.5.2.0, aeson-1.5.1.0, aeson-1.5.0.0, aeson-1.4.7.1,
aeson-1.4.7.0, aeson-1.4.6.0, aeson-1.4.5.0, aeson-1.4.4.0, aeson-1.4.3.0,
aeson-1.4.2.0, aeson-1.4.1.0, aeson-1.4.0.0, aeson-1.3.1.1, aeson-1.3.1.0,
aeson-1.3.0.0, aeson-1.2.4.0, aeson-1.2.3.0, aeson-1.2.2.0, aeson-1.2.1.0,
aeson-1.2.0.0, aeson-1.1.2.0, aeson-1.1.1.0, aeson-1.1.0.0, aeson-1.0.2.1,
aeson-1.0.2.0, aeson-1.0.1.0, aeson-1.0.0.0, aeson-0.11.3.0, aeson-0.11.2.1,
aeson-0.11.2.0, aeson-0.11.1.4, aeson-0.11.1.3, aeson-0.11.1.2,
aeson-0.11.1.1, aeson-0.11.1.0, aeson-0.11.0.0, aeson-0.9.0.1, aeson-0.9.0.0,
aeson-0.8.1.1, aeson-0.8.1.0, aeson-0.8.0.2, aeson-0.7.0.6, aeson-0.7.0.4,
aeson-0.6.2.1, aeson-0.6.2.0, aeson-0.6.1.0, aeson-0.6.0.2, aeson-0.6.0.1,
aeson-0.6.0.0, aeson-0.5.0.0, aeson-0.4.0.1, aeson-0.4.0.0, aeson-0.3.2.14,
aeson-0.3.2.13, aeson-0.3.2.12, aeson-0.3.2.11, aeson-0.3.2.10, aeson-0.3.2.9,
aeson-0.3.2.8, aeson-0.3.2.7, aeson-0.3.2.6, aeson-0.3.2.5, aeson-0.3.2.4,
aeson-0.3.2.3, aeson-0.3.2.2, aeson-0.3.2.1, aeson-0.3.2.0, aeson-0.3.1.1,
aeson-0.3.1.0, aeson-0.3.0.0, aeson-0.2.0.0, aeson-0.1.0.0, aeson-0.10.0.0,
aeson-0.8.0.1, aeson-0.8.0.0, aeson-0.7.0.5, aeson-0.7.0.3, aeson-0.7.0.2,
aeson-0.7.0.1, aeson-0.7.0.0 (has the same characteristics that caused the
previous version to fail: excluded by constraint '>=2 && <3' from 'odd-jobs')
[__3] fail (backjumping, conflict set: aeson, odd-jobs, servant-server)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: odd-jobs, aeson, servant-server,
servant-static-th
Try running with --minimize-conflict-set to improve the error message.

I will investigate later. Thank you

[peterbecich]

Closing, the actual issue is haskell-servant/servant#1467