stack resolver is outdated

https://github.com/koalaman/shellcheck/blob/24d96714d8d8f9e932f22bf182780452718e3139/stack.yaml#L5

The latest release for ghc-8.10.7 is lts-18.28, and of course newer resolvers are available. #3537 requires lts-22.6.

https://www.stackage.org/