Remove redundant cast

By: md_5 <git@md-5.net>

paper-server/nms-patches/AdvancementDataPlayer.patch

@@ -6,7 +6,7 @@
                          if (advancement == null) {
 -                            AdvancementDataPlayer.LOGGER.warn("Ignored advancement '{}' in progress file {} - it doesn't exist anymore?", entry.getKey(), this.e);
 +                            // CraftBukkit start
-+                            if (((MinecraftKey) entry.getKey()).b().equals("minecraft")) {
++                            if (entry.getKey().b().equals("minecraft")) {
 +                                AdvancementDataPlayer.LOGGER.warn("Ignored advancement '{}' in progress file {} - it doesn't exist anymore?", entry.getKey(), this.e);
 +                            }
 +                            // CraftBukkit end