Use GHC2021

[michaelpj]

I think this looks fairly good, cuts down our extension spam a bit.

[soulomoon]

I like this idea.

[jhrcek]

I like this idea especially in a codebase that's more like an application than like a library.
FYI I resolved merge conflict caused by my PR and pushed to this branch.
Let me know if you find it inappropriate for people to push to other people's branches.

[michaelpj]

Let me know if you find it inappropriate for people to push to other people's branches.

I think it's generally helpful in the case of resolving conflicts (unless you do it wrong :p ). So thanks!