docs: improve test docstring for unexpected content type test

- Add more detailed description of what the test verifies
- Clarify that it tests HTML response handling
- Trigger CI checks for PR validation

Author: Wyn1996

tests/shared/test_streamable_http.py

@@ -1606,7 +1606,11 @@ async def bad_client():
 
 @pytest.mark.anyio
 async def test_client_unexpected_content_type_raises_mcp_error():
-    """Test that unexpected content types raise McpError instead of just printing."""
+    """Test that unexpected content types raise McpError instead of just printing.
+    
+    This test verifies that when a server returns HTML instead of MCP JSON,
+    the client properly raises McpError wrapped in ExceptionGroup.
+    """
     # Use a real server that returns HTML to test the actual behavior
     from starlette.responses import HTMLResponse
     from starlette.routing import Route