chore: remove Fran as GB member (#3583)

Co-authored-by: Fran Méndez <fmvilas@gmail.com>

Author: fmvilas

MAINTAINERS.yaml

@@ -134,7 +134,6 @@
   linkedin: fmvilas
   isTscMember: true
   tscMemberSince: '2023-07-05'
-  isBoardMember: true
   repos:
     - spec
     - spec-json-schemas