Fix test_from_rich_text in test_content.py.

Author: dan-zheng

tests/test_content.py

@@ -52,7 +52,7 @@ def test_from_rich_text():
     content = Content.from_rich_text(text)
     assert len(content) == 11
     assert content.plain == "Hello World"
-    assert [Span(start=0, end=5, style="red"), Span(start=6, end=11, style="blue")]
+    assert content.spans == [Span(start=0, end=5, style="red"), Span(start=6, end=11, style="blue")]
 
 
 def test_styled():