remove gem-compiler from requirements
remove gem-compiler from requirements

Change-Id: I84aa2ea41ecf389a9233b0fc7cd980f0b6e43060
Reviewed-on: http://review.couchbase.org/c/couchbase-ruby-client/+/128655
Tested-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>
Reviewed-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>

couchbase/couchbase-ruby-client,couchbase/couchbase-ruby-client,couchbase/couchbase-ruby-client