Add site-specific quirk for gitlab.gnome.org

Fixes #8509

doc/help/settings.asciidoc

@@ -2770,6 +2770,7 @@ Valid values:
 
  * +ua-google+
  * +ua-googledocs+
+ * +ua-gnome-gitlab+
  * +js-whatsapp-web+
  * +js-discord+
  * +js-string-replaceall+

qutebrowser/browser/webengine/webenginesettings.py

@@ -508,6 +508,20 @@ def _init_site_specific_quirks():
     #               "Safari/{webkit_version}")
     firefox_ua = "Mozilla/5.0 ({os_info}; rv:136.0) Gecko/20100101 Firefox/139.0"
 
+    # Needed for gitlab.gnome.org which blocks old Chromium versions outright,
+    # except when QtWebEngine/... is in the UA.
+    #
+    # We could further modify the UA to just "qutebrowser" or something so we don't get
+    # Anubis at all, but it looks like their Anubis triggers to more than just
+    # Mozilla/5.0 (also AppleWebKit/... and Chromium/... possibly?), so at that point
+    # I'm not sure if we can strip down the UA so much without breaking
+    # something in GitLab as well.
+    not_mozilla_ua = (
+        "Mozilla/5.0 ({os_info}) AppleWebKit/{webkit_version} (KHTML, like Gecko) "
+        "{qt_key}/{qt_version} {upstream_browser_key}/{upstream_browser_version_short} "
+        "Safari/{webkit_version}"
+    )
+
     def maybe_newer_chrome_ua(at_least_version):
         """Return a new UA if our current chrome version isn't at least at_least_version."""
         current_chome_version = version.qtwebengine_versions().chromium_major
@@ -528,6 +542,7 @@ def _init_site_specific_quirks():
         # to keep your account secure" error.
         # https://github.com/qutebrowser/qutebrowser/issues/5182
         ("ua-google", "https://accounts.google.com/*", firefox_ua),
+        ("ua-gnome-gitlab", "https://gitlab.gnome.org/*", not_mozilla_ua),
     ]
 
     for name, pattern, ua in user_agents:

qutebrowser/config/configdata.yml

@@ -658,6 +658,7 @@ content.site_specific_quirks.skip:
     valid_values:
       - ua-google
       - ua-googledocs
+      - ua-gnome-gitlab
       - js-whatsapp-web
       - js-discord
       - js-string-replaceall