hadrian: Enforce the usage of GHC >=9.8.1 for ghci-multi

GHC 9.6 no good when it comes to multi-repl stuff, despite being well
within the range of n-2 releases for bootstrapping, when the script was
adapted to load haddock, in !12851

hadrian/ghci-multi-cabal.in

 #!/usr/bin/env sh
 
 RUN_GHC=@WithGhc@
-if [[ $(printf "9.4.0\n%s\n" $($RUN_GHC --numeric-version) | sort -uV | head -n 1) != "9.4.0" ]]; then echo "Multi-repl needs at least GHC-9.4.1"; exit 1; fi
+if [[ $(printf "9.8.1\n%s\n" $($RUN_GHC --numeric-version) | sort -uV | head -n 1) != "9.8.1" ]]; then echo "Multi-repl needs at least GHC-9.8.1"; exit 1; fi
 
 # This file is generated by configure from ghci-multi.in