Fixed #35876 -- Displayed non-ASCII fieldset names when rendering ModelAdmin.fieldsets.

Thank you to Namhong Kim for the report, and to Mariusz Felisiak and Marijke Luttekes for the review.

Regression in 01ed59f753.

tests/admin_views/admin.py

@@ -237,6 +237,7 @@ class ArticleAdmin(ArticleAdminWithExtraUrl):
             "Some other fields",
             {"classes": ("wide",), "fields": ("date", "section", "sub_section")},
         ),
+        ("이름", {"fields": ("another_section",)}),
     )
 
     # These orderings aren't particularly useful but show that expressions can