macos_installer_handler.py: List n-3 apps

Thanks @jazzzny for idea and implementation

opencore_legacy_patcher/support/macos_installer_handler.py

@@ -566,6 +566,11 @@ class RemoteInstallerCatalog:
                         newest_apps.pop(ia)
                         break
 
+        # Remove EOL versions (n-3)
+        for ia in list(newest_apps):
+            if newest_apps[ia]["Version"].split('.')[0] < supported_versions[-3]:
+                newest_apps.pop(ia)
+
         return newest_apps