Bump admin stylesheet cache key

tests/test_admin.py

@@ -15,7 +15,7 @@ def test_admin_page_shows_operator_views_without_create_form(tmp_path: Path) ->
 
     assert response.status_code == 200
     assert response.headers["cache-control"] == "no-store"
-    assert '<link href="/admin.css?v=2" rel="stylesheet">' in response.text
+    assert '<link href="/admin.css?v=3" rel="stylesheet">' in response.text
     assert '<script src="/admin-tables.js?v=2" defer></script>' in response.text
     assert "Operator console" in response.text
     assert "Generate credentials" not in response.text