* Forbid solving for hashtables 1.3
On modern gccs, this sometimes causes build failures, see
https://github.com/gregorycollins/hashtables/issues/97
* Propagate constraint to package.yaml too
* stack98: include valid hashtables version
* stack92: add valid hashtables version
* stack94: add valid hashtables version
* stack96: add valid hashtables version
System.IO.hGetContents' was the latest paper cut; I could keep
supporting ghc 8.10.7, or at least 9.0-9.4, released 2021-2023;
but feck it. Debian Stable has 9.6 and this time can be better spent.