[feature request] 1.21.4 compatibility

[quiquelhappy]

heya, minor to none API changes.

[14:33:36 WARN]: Caused by: java.lang.RuntimeException: No NMSWrapper implementation for UNSUPPORTED version UNSUPPORTED
[14:33:36 WARN]:        at ImageFrame-1.7.11.0.jar//com.loohp.imageframe.nms.NMS.getInstance(NMS.java:43)
[14:33:36 WARN]:        at ImageFrame-1.7.11.0.jar//com.loohp.imageframe.utils.MapUtils.lambda$getMapOrCreateMissing$5(MapUtils.java:374)
[14:33:36 WARN]:        at org.bukkit.craftbukkit.scheduler.CraftFuture.run(CraftFuture.java:88)
[14:33:36 WARN]:        at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:474)
[14:33:36 WARN]:        at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1805)
[14:33:36 WARN]:        at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1666)
[14:33:36 WARN]:        at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1331)
[14:33:36 WARN]:        at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:341)
[14:33:36 WARN]:        ... 1 more
[14:33:36 WARN]: Caused by: java.lang.ClassNotFoundException: com.loohp.imageframe.nms.UNSUPPORTED
[14:33:36 WARN]:        at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:197)
[14:33:36 WARN]:        at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:164)
[14:33:36 WARN]:        at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
[14:33:36 WARN]:        at java.base/java.lang.Class.forName0(Native Method)
[14:33:36 WARN]:        at java.base/java.lang.Class.forName(Unknown Source)
[14:33:36 WARN]:        at java.base/java.lang.Class.forName(Unknown Source)
[14:33:36 WARN]:        at io.papermc.reflectionrewriter.runtime.AbstractDefaultRulesReflectionProxy.forName(AbstractDefaultRulesReflectionProxy.java:68)
[14:33:36 WARN]:        at io.papermc.paper.pluginremap.reflect.PaperReflectionHolder.forName(Unknown Source)
[14:33:36 WARN]:        at ImageFrame-1.7.11.0.jar//com.loohp.imageframe.nms.NMS.getInstance(NMS.java:37)
[14:33:36 WARN]:        ... 8 more