Fix blog post link (#12282)

Author: stsewd

readthedocs/projects/notifications.py

@@ -187,7 +187,7 @@
                 This project has a deploy key with write access to the repository.
                 For protection against abuse we've restricted use of these deploy keys.
                 A read-only deploy key will need to be set up <b>before July 31, 2025</b> to continue building this project.
-                Read more about this in our <a href="https://about.readthedocs.com/blog/2025/05/ssh-keys-with-write-access/">blog post</a>.
+                Read more about this in our <a href="https://about.readthedocs.com/blog/2025/07/ssh-keys-with-write-access/">blog post</a>.
                 """
             ).strip(),
         ),