stack update to lts-14.6 and ghc 8.6.5

[ynishi]

I built via stack today, and failed(It may be no problem to build other environment, like in docker container.).

• environment
  • Debian 9.4
  • stack 2.1.3
  • installed ghc 8.6.5

I tried to update stack.yaml and success without change app source(just reformat to pass test). How about update?

change

• update stack.yaml
  • update resolver to lts-14.6
  • update hindent version
  • add stylish-haskell version
• hfmt source(because stack test failed)

diff

https://github.com/danstiner/hfmt/compare/master...ynishi:support_ghc_8.6.5?expand=1

check

• stack build, test, install succeeded.
• hfmt -w . command worked.
• but no completely check all features.

[danstiner]

Thanks for the cleanup, merged to master: https://github.com/danstiner/hfmt/commit/b40725f4125d1985a269b5f50785c0a2a9ef1a52

[ynishi]

Thanks for to marge!

[danstiner]

Of course!