Fix GitHub Pages challenge TXT for davidasync.is-a.dev

Correct a one-character typo so the published record matches GitHub's verification value.

Co-authored-by: Cursor <cursoragent@cursor.com>

domains/_github-pages-challenge-davidasync.davidasync.json

@@ -4,6 +4,6 @@
     "email": "davidasync@gmail.com"
   },
   "records": {
-    "TXT": "9c8d8d2d2ac7481fb7bebe97da4f66"
+    "TXT": "9c8d8d2d2ac7481fb75ebe97da4f66"
   }
 }