Use Set instead of List internally in JsonKeyReader

We might as well do this as we aren't generating the sequence lazily.

Signed-off-by: Graham <gpe@openrs2.org>

archive/src/main/kotlin/org/openrs2/archive/key/JsonKeyReader.kt

@@ -14,7 +14,7 @@ public class JsonKeyReader @Inject constructor(
     @Json private val mapper: ObjectMapper
 ) : KeyReader {
     override fun read(input: InputStream): Sequence<XteaKey> {
-        val keys = mutableListOf<XteaKey>()
+        val keys = mutableSetOf<XteaKey>()
         val root = mapper.readTree(input)
 
         when {