Build matrix going forward

[blackgnezdo]

As an aside, building with Stack is now problematic because a number of packages were dropped after nightly-2024-12-09. I first noticed this with hlint, but discrimination was also dropped, which is relevant to proto-lens. Given that Stack is geared towards reproducible builds with fixed versions, it is going to be awkward to continue having the continuous build matrix based on Stack; would there be any opposition to switching the matrix to be for Cabal and use a single fixed snapshot with Stack?

Originally posted by @chungyc in #507

[blackgnezdo]

The goal is to keep the code compatible with a range of GHC versions. Is it less practical to do with stack now? Is there some recent change you have in mind?