dateMenu: Mark string for translation

T_() is a convenience shortcut for looking up a string from the
locale defined by LC_TIME, but it isn't recognized as a gettext
keyword. To do that, we also have to wrap the string in N_() or
NC_().

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2246>

js/ui/dateMenu.js

@@ -219,7 +219,7 @@ class EventsSection extends St.Button {
                 /* Translators: Shown in calendar event list as the start/end of events
                  * that only show day and month
                  */
-                format = T_('%m/%d');
+                format = T_(N_('%m/%d'));
             else
                 format = '%x';