[Nomination] Adding Mozilla representative to security group

Hey folks,

I recently moved from Redhat to Mozilla, still working on compiler /
build issues. I'd like to both

- resign as a member of Redhat

- apply as a member of Mozilla

Mozilla's mission makes it very sensible to compiler security flags, so
it makes sense (at least to me) to have it represented in the group.

Although I've been a discrete member of group, I'm still actively
dealing with some security-related patches [0] and blogging about it [1,2]

[0] https://reviews.llvm.org/D137707
[1] https://developers.redhat.com/articles/2022/06/02/use-compiler-flags-stack-protection-gcc-and-clang
[2] https://developers.redhat.com/articles/2022/09/29/benefits-limitations-flexible-array-members

Differential Revision: https://reviews.llvm.org/D138898