Latest Hackage does not build on old GHC

The latest Hackage release has a lower bound on `base >= 4.11`, corresponding to GHC 8.4. However, I've recently noticed that it fails to build on 8.4 in the [`persistent`]() CI.

[`liftA2` is exported from `Prelude` as of GHC 9.6](https://github.com/haskell/core-libraries-committee/blob/main/guides/export-lifta2-prelude.md). These function calls were added in #279.