[issue41919] Modify test_codecs to use the new codecs.unregister() function

[STINNER Victor]

Change by STINNER Victor <vstinner at python.org>:


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title: Move the codecs.register operation to testcases -> Modify test_codecs to use the new codecs.unregister() function

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue41919>
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