Use formatting print to show underlying error message

This appears to be a typo where "Println" was used instead of "Printf"

collector/collector.go

@@ -442,7 +442,7 @@ func fetchRemoteConfig(url string) (*Config, error) {
 
 	if !HasValidHeader(string(body)) {
 		// TODO: Print a warning when we implement proper logging
-		fmt.Println("No valid header in remote config: %w", err)
+		fmt.Printf("No valid header in remote config: %w", err)
 		return result, nil
 	}