Fix beta channel updates breakage due to browser_specific_settings override.

Author: hackademix

src/manifest.json

@@ -9,6 +9,10 @@
     }
   },
   "browser_specific_settings": {
+    "gecko": {
+      "id":  "{73a6fe31-595d-460b-a920-fcc0f8843232}",
+      "strict_min_version": "59.0"
+    },
     "gecko_android": {}
   },
   "version": "11.4.29rc3",