Gsutil: 在 Python 3.9 上遇到错误 - AttributeError: module 'base64' has no attribute 'decodestring'

微软的应用中心最近更新到 Python 3.9，我在上面运行 gsutil 时遇到如下错误：

Traceback (most recent call last):
  File "/usr/local/bin/gsutil", line 5, in <module>
    from gslib.__main__ import main
  File "/usr/local/lib/python3.9/site-packages/gslib/__main__.py", line 92, in <module>
    from gslib.command_runner import CommandRunner
  File "/usr/local/lib/python3.9/site-packages/gslib/command_runner.py", line 64, in <module>
    from gslib.tests.util import HAS_NON_DEFAULT_GS_HOST
  File "/usr/local/lib/python3.9/site-packages/gslib/tests/util.py", line 126, in <module>
    TEST_ENCRYPTION_KEY1_SHA256_B64 = Base64Sha256FromBase64EncryptionKey(
  File "/usr/local/lib/python3.9/site-packages/gslib/utils/encryption_helper.py", line 152, in Base64Sha256FromBase64EncryptionKey
    decoded_bytes = base64.decodestring(csek_encryption_key)
AttributeError: module 'base64' has no attribute 'decodestring'

此错误由gsutil -o Credentials:gs_service_key_file=./mykey.json cp src_url dist_url命令触发。

关于如何让这个命令在 Python 3.9 上工作的任何想法？ 谢谢你。