Bump version to 2.12.0-beta1 (#2908)

Author: mokagio

package-lock.json

@@ -6,7 +6,7 @@
     "email": "[email protected]"
   },
   "productName": "Simplenote",
-  "version": "2.11.0",
+  "version": "2.12.0-beta1",
   "main": "desktop/index.js",
   "license": "GPL-2.0",
   "homepage": "https://simplenote.com",