return 204 no-content if yaml not mutated

[bradrydzewski]

I recommend returning a 204 no content if the yaml is not mutated (no changeset attributes defined, etc). The reason is that when no content is returned, Drone will fallback to the default fetch logic. This is important for installations that are still using 0.8 configuration files, since the default logic will handle conversion.

(PS sorry for not being more proactive with a pull request, but the Drone backlog is keeping me too busy right now)

[microadam]

Good to know! I will add that in when I have some time. Should be a fairly simple change