fix check links for unpublished advisories

docs/source/conf.py

@@ -188,6 +188,8 @@ linkcheck_ignore = [
     r"https?://(localhost|127.0.0.1).*",  # ignore localhost references in auto-links
     r".*/rest-api.html#.*",  # ignore javascript-resolved internal rest-api links
     r"https://linux.die.net/.*",  # linux.die.net seems to block requests from CI with 403 sometimes
+    # don't check links to unpublished advisories
+    r"https://github.com/jupyterhub/jupyterhub/security/advisories/.*",
 ]
 linkcheck_anchors_ignore = [
     "/#!",