MAINTAINERS: add Sabrina to TLS maintainers

Sabrina has been very helpful reviewing TLS patches, fixing bugs,
and, I believe, the last one to implement any major feature in
the TLS code base (rekeying). Add her as a maintainer.

Acked-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250903212054.1885058-1-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>