Improvements for unregistering commands

Author: Despical

src/main/java/me/despical/commandframework/CommandFramework.java

@@ -309,7 +309,7 @@ public void unregisterCommand(@NotNull String commandName) {
 			}
 
 			this.commands.remove(command);
-			new HashMap<>(this.subCommands).keySet().stream().filter(subCmd -> subCmd.name().startsWith(name)).forEach(this.subCommands::remove); // Copy elements to new map to avoid modification exception
+			this.subCommands.entrySet().removeIf(subEntry -> subEntry.getKey().name().startsWith(name));
 		});
 	}