Check for breaking changes in rake graphql:schema:dump

[cjoudrey]

Once rmosolgo/graphql-ruby#384 is merged we can verify if any breaking changes were made. If so, the rake task will early exit unless FORCE=1 is specified.

re:

swapi-graphql-ruby/lib/tasks/graphql.rake

Lines 7 to 9 in 436044b

	# TODO - Once https://github.com/rmosolgo/graphql-ruby/pull/384 is merged we can
	# verify if any breaking changes were made. If so, the rake task will early
	# exit unless `FORCE=1` is specified.