[llvm] [Github] Add Zlib at build time to CI container (PR #123489)

[Tom Stellard via llvm-commits]

tstellar wrote:

> > Is there a plan to fix the test too?
> 
> This fixes the test. I want to fix the requires in the test too so it actually checks for what it needs, but putting that on the back-burner for now.

OK, can you file an issue for this so it doesn't get forgotten?


https://github.com/llvm/llvm-project/pull/123489