Add support for GHC 9.10, remove support for GHC 9.4

[tfausak]

https://github.com/tfausak/imp/pull/24

[tfausak]

Timing on CI isn't reliable, but 9.10 seems to be about the same as 9.8:

• 9.8 https://github.com/tfausak/rattletrap/actions/runs/8774139315/job/24075027363
  • built in 52s, tested in 5m13s
• 9.10 https://github.com/tfausak/rattletrap/actions/runs/9148950390/job/25152060347
  • built in 39s, tested in 5m22s