Changes to work with LTS-16.31 (GHC-8.8.4)

[saurabhnanda]

No description provided.

[knrafto]

Thank you! Github says there are conflicts, can you resolve them?

[saurabhnanda]

@knrafto just a single conflict in stack.yaml. What do you want the stack resolver in master to be? LTS-12.1 or LTS-16.31? Or should we have different stack.yaml files? One for each version of GHC that this package works with?

[knrafto]

The GHC version in master is ancient only because it hasn't been touched in a while.

I cherry-picked your commit to master and fixed it up so it would build on my machine. I had to set text-icu >= 0.7.1.0 to build on macOS, so I bumped the stack resolver to lts-18.21, GHC 8.10.7. Does that work for you? If not we can do separate stack files.