Can't install with Stack

I'm sorry if this is not the right place to bring this up, but wasn't sure where to turn. You mention in the readme that installation is just running stack install hfmt. I did so, and this is what happened. I'm very new to Haskell, so I'm unsure how to resolve this.

λ stack install hfmt                                                                                                                                                                [~] [14:43]

Error: While constructing the build plan, the following exceptions were encountered:

In the dependencies for hfmt-0.2.1:
    haskell-src-exts-1.20.2 from stack configuration does not match <1.20  (latest matching version is 1.19.1)
    stylish-haskell must match ==0.8.*, but the stack configuration has no specified version  (latest matching version is 0.8.1.0)
needed since hfmt is a build target.

Some different approaches to resolving this:

  * Consider trying 'stack solver', which uses the cabal-install solver to attempt to find some working build configuration. This can be convenient when dealing with many complicated
    constraint errors, but results may be unpredictable.

  * Recommended action: try adding the following to your extra-deps in /home/ahstro/.stack/global-project/stack.yaml:

- haskell-src-exts-1.19.1
- stylish-haskell-0.8.1.0

Plan construction failed.

danstiner / hfmt

Can't install with Stack #36