Use ellipsis for ellipsistrim template filter

wagtail/admin/templatetags/wagtailadmin_tags.py

@@ -85,7 +85,7 @@ def ellipsistrim(value, max_length):
         truncd_val = value[:max_length]
         if not len(value) == (max_length + 1) and value[max_length + 1] != " ":
             truncd_val = truncd_val[:truncd_val.rfind(" ")]
-        return truncd_val + "..."
+        return truncd_val + "…"
     return value