update: 解决python 3.8及以上版本，HtmlResult和HtmlTestReport的warning

[Vancheung]

RuntimeWarning: line buffering (buffering=1) isn't supported in binary mode, the default buffer size will be used file = builtins.open(filename, mode, buffering)

[tencent-adm]

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:white_check_mark: Vancheung
:x: vanzhang

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