Build against multiple versions of GHC

[Profpatsch]

In addition to testing against multiple versions of bazel (see #452), we should make an effort to be compatible against multiple versions of GHC (especially since there will be a GHC release every six months from now on).

nixpkgs keeps a few ghc package sets around, so it should be easy to run our test suite against them.

[GuillaumeGen]

Is the solution introduced by #1790 sufficient to close it (it tests all the GHC versions listed in

rules_haskell/haskell/gen_ghc_bindist.py

Line 18 in 5ac5e63

VERSIONS = [

), or do we want also to have a mechanism to test against all GHC versions provide by nixpkgs?

[avdv]

This is quite related to #1878

Currently we are checking GHC versions 9.2, 9.4, and 9.6 on CI. Support for GHC 9.8 is planned.