[llvm] Bump required minimal Z3 version from 4.7.1 to 4.8.9 (PR #96682)

[Balazs Benics via llvm-commits]

steakhal wrote:

@whisperity Feel free to revert this is it blocks you or if anyone else is blocked.
Otherwise, on Monday I'll re-land the dependent 2 patches.

https://github.com/llvm/llvm-project/pull/96682