Bump to 1.19.0 stable (ScratchAddons#3354)

Author: WorldLanguages

manifest.json

@@ -3,7 +3,7 @@
   "name": "__MSG_extensionName__",
   "description": "__MSG_extensionDescription__",
   "version": "1.19.0",
-  "version_name": "1.19.0-prerelease",
+  "version_name": "1.19.0",
   "default_locale": "en",
   "background": {
     "page": "background/background.html"