Remove ghc 9.0 test from CI.

Author: jgm

.github/workflows/ci.yml

@@ -10,8 +10,6 @@ jobs:
       fail-fast: false
       matrix:
         versions:
-          - ghc: '9.0'
-            cabal: '3.8'
           - ghc: '9.2'
             cabal: '3.10'
           - ghc: '9.4'