fix MV3 dynamic script injection

Author: cpiber

src/manifest_v3.ts

@@ -41,6 +41,7 @@ const manifest: browser._manifest.WebExtensionManifest = {
   permissions: [
     'storage',
     'offscreen',
+    'scripting',
   ],
   host_permissions: [
     // Only firefox requires this, and the subdomain must be completely specified, otherwise the request fails