fix: update regex comment

plugin/builtin/imagetagtransformer/ImageTagTransformer.go

@@ -148,7 +148,7 @@ func (p *plugin) findContainers(obj map[string]interface{}) error {
 }
 
 func isImageMatched(s, t string) bool {
-	// Tag values are limited to [a-zA-Z0-9_.-].
+	// Tag values are limited to [a-zA-Z0-9_.-{}].
 	pattern, _ := regexp.Compile("^" + t + "(@sha256)?(:[a-zA-Z0-9_.-{}]*)?$")
 	return pattern.MatchString(s)
 }