Add stack 2.3.3

[avh4]

Stack 2.3.3 was released on 2020-08-05. Stack 2.3.3 is also now the preinstalled version for the github-hosted runners [1], so currently github action builds using setup-haskell with stack-version: latest produce the build warning "stack 2.3.1 was not found in the cache."

[avh4]

Oh, oops, I guess I'll have to check this out locally and recompile dist

[avh4]

Hmm... I tried following the instructions in docs/contributors.md, and husky appears to run on commit and on push, but it doesn't appear to be compiling the changes to dist.