Support LLVM 19
LLVM 19 has been released so we need to bump the support window to include it.
In order to do this we need to update one of the CI jobs to use LLVM 19.
Due to a large amount of spam we do not allow new users to create repositories, they are "external" users. If you are a new user and want to create a repository, for example for forking GHC, open a new issue on ghc/ghc using the "get-verified" issue template
LLVM 19 has been released so we need to bump the support window to include it.
In order to do this we need to update one of the CI jobs to use LLVM 19.