Added a patch to remove duplicates

patches/animelist-remove-duplicates/animelist-remove-duplicates.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"github.com/animenotifier/arn"
+)
+
+func main() {
+	for animeList := range arn.StreamAnimeLists() {
+		animeList.RemoveDuplicates()
+		animeList.Save()
+	}
+}