revert #22 and declare v48 compatibility

Author: thomasnemer

metadata.json

@@ -3,7 +3,6 @@
   "description": "Hides the classic title bar of maximized X.Org windows",
   "url": "https://github.com/alecdotninja/no-titlebar-when-maximized",
   "uuid": "[email protected]",
-  "shell-version": ["45", "46", "47"],
-  "session-modes": ["user", "unlock-dialog"],
-  "version": 17
+  "shell-version": ["45", "46", "47", "48"],
+  "version": 18
 }