fix edit snippet use case

src/snippets/use_cases/edit.clj

@@ -9,7 +9,7 @@
    [:map {:closed true}
     [:markdown {:optional true} :string]
     [:title {:optional true} :string]
-    [:tags [:seqable :string]]
+    [:tags {:optional true} [:seqable :string]]
     [:slug {:optional true} :string]]))
 
 (defn edit-snippet [id patch]