fix: bump written version of dialog API to 1.21.8 (#654)

Author: tgbhy

src/content/docs/paper/dev/api/dialogs.mdx

@@ -2,7 +2,7 @@
 title: Dialog API
 description: A guide to the dialog API introduced in 1.21.7.
 slug: paper/dev/dialogs
-version: 1.21.7
+version: 1.21.8
 sidebar:
   badge:
     text: Experimental