API server return error 500 on artifact quota exhaustion

[hnez]

The server should return 413 Content Too Large instead of 500 Internal Server Error.
The source of the generic server error is here:

forrest/src/artifacts.rs

Lines 124 to 126 in 7a95060

	if !artifact.consume_quota(data.len() as u64) {
	bail!("Quota exceeded");
	}

Thanks to @Bastian-Krause for reporting this to me.