www/firefox{-esr} depends on llmv13 and not default 15

Hello all,

bsd.default-versions.mk LLVM is 15 and bsd.gecko.mk is also configured to
use default version llvm.

Can't understand why firefox build still depends on llvm13 or am I missing
something?

Thanks,

-- 
Nuno Teixeira
FreeBSD Committer (ports)