Deprecation warning: showVersion

[langston-barrett]

The following deprecation warning shows up when building abcBridge:

[1 of 1] Compiling Main             ( /home/travis/build/GaloisInc/abcBridge/dist-newstyle/build/x86_64-linux/ghc-8.4.3/abcBridge-0.17.1/setup/setup.hs, /home/travis/build/GaloisInc/abcBridge/dist-newstyle/build/x86_64-linux/ghc-8.4.3/abcBridge-0.17.1/setup/Main.o )
/home/travis/build/GaloisInc/abcBridge/dist-newstyle/build/x86_64-linux/ghc-8.4.3/abcBridge-0.17.1/setup/setup.hs:111:51: warning: [-Wdeprecations]
    In the use of ‘showVersion’
    (imported from Distribution.Version, but defined in Distribution.Types.Version):
    Deprecated: "Use prettyShow. This function will be removed in Cabal-3.0 (estimated Oct 2018)"
    |
111 |     putStrLn $ unwords ["Cabal library version:", showVersion Distribution.Simple.Utils.cabalVersion]
    |                                                   ^^^^^^^^^^^
/home/travis/build/GaloisInc/abcBridge/dist-newstyle/build/x86_64-linux/ghc-8.4.3/abcBridge-0.17.1/setup/setup.hs:117:28: warning: [-Wdeprecations]
    In the use of ‘showVersion’
    (imported from Distribution.Version, but defined in Distribution.Types.Version):
    Deprecated: "Use prettyShow. This function will be removed in Cabal-3.0 (estimated Oct 2018)"
    |
117 |         ([(packageVersion, showVersion version)] ++ filter ((/=packageVersion) . fst) env)
    |                            ^^^^^^^^^^^
Linking /home/travis/build/GaloisInc/abcBridge/dist-newstyle/build/x86_64-linux/ghc-8.4.3/abcBridge-0.17.1/setup/setup ...

See https://travis-ci.org/GaloisInc/abcBridge/jobs/414719905#L545.