update ffi in Gemfile.lock
update ffi in Gemfile.lock

Known moderate severity security vulnerability detected in ffi < 1.9.24 defined in Gemfile.lock.
Gemfile.lock update suggested: ffi ~> 1.9.24.
stonefl/stonefl.github.io,stonefl/stonefl.github.io,stonefl/stonefl.github.io