[llvm] [Nomination] Add ST representative to Security group (PR #93176)

[Yvan Roux via llvm-commits]

yroux wrote:

Thanks a lot for your Trust!

I'll merge the PR since the majority is now reached and the 5 business days are passed.

Hope to see you in the next sync meeting

https://github.com/llvm/llvm-project/pull/93176