Drop support for gnome-shell < 3.8

metadata.json

@@ -3,9 +3,9 @@
   "description": "This extension disables the top left hot corners. You can still click on Activities or press the dedicated key to reach the overview. Since 3.8, should work with other extensions modifying the Activities button. On versions prior to 3.8, may not disable other hotcorners in multiscreen configurations and won't work on fallback/flashback mode.",
   "name": "No Topleft Hot Corner",
   "shell-version": [
-    "3.18", "3.16", "3.14", "3.12", "3.10", "3.8", "3.6", "3.4"
+    "3.20", "3.18", "3.16", "3.14", "3.12", "3.10", "3.8"
   ],
   "url": "https://github.com/HROMANO/nohotcorner/",
   "uuid": "[email protected]",
-  "version": 12
+  "version": 13
 }