feat: submission url

Add URL field to Submission struct in Furaffinaty package

pkg/furaffinaty/models/submission.go

@@ -1,9 +1,12 @@
 package models
 
-import "time"
+import (
+	"time"
+)
 
 type Submission struct {
 	ID          string          `json:"id,omitempty"`
+	Url         string          `json:"url,omitempty"`
 	Title       string          `json:"title,omitempty"`
 	Tags        []string        `json:"tags,omitempty"`
 	Artist      Artist          `json:"artist"`