www/gitlab-ce: Use grpc 1.30.2

We currently see problems and gitlab suggested to use grpc 1.30.2:
https://gitlab.com/gitlab-org/gitlab/-/issues/345693#note_734676746

Newer version of grpc and google-protobuf have known bugs.

The open bug that license files cannot not be handled is tracked here:
https://gitlab.com/gitlab-org/gitlab/-/issues/345693
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=259848