Disable pretty printing for advancement saving

Reduces json size by about 25%
Not sure why advancements even had pretty printing enabled.
My best guess was by accident on mojang's part, especially since stats json files don't have pretty printing.

paper-server/patches/sources/net/minecraft/server/PlayerAdvancements.java.patch

@@ -1,5 +1,14 @@
 --- a/net/minecraft/server/PlayerAdvancements.java
 +++ b/net/minecraft/server/PlayerAdvancements.java
+@@ -50,7 +50,7 @@
+ public class PlayerAdvancements {
+ 
+     private static final Logger LOGGER = LogUtils.getLogger();
+-    private static final Gson GSON = (new GsonBuilder()).setPrettyPrinting().create();
++    private static final Gson GSON = (new GsonBuilder()).create(); // Paper - Remove pretty printing from advancements
+     private final PlayerList playerList;
+     private final Path playerSavePath;
+     private AdvancementTree tree;
 @@ -63,6 +63,7 @@
      private AdvancementHolder lastSelectedTab;
      private boolean isFirstPacket = true;