Remove dependency on six

[xiangyan99]

https://github.com/Azure/azure-sdk-for-python/issues/26893.

Ref: https://github.com/Azure/azure-sdk-for-python/pull/25565

• [ ] azure-ai-anomalydetector
• [ ] azure-appconfiguration - code gen
• [ ] azure-security-attestation
• [ ] azure-ai-language-questionanswering
• [ ] azure-communication
• [ ] azure-containerregistry - test only?
• [x] azure-cosmos
• [ ] azure-eventgrid
• [x] azure-eventhub
• [ ] azure-ai-ml
• [ ] azure-monitor
• [ ] azure-search-documents
• [ ] azure-storage
• [ ] azure-data-tables
• [ ] azure-ai-translation-document
• [ ] azure-media-videoanalyzer-edge
• [x] azure-identity

[azure-sdk]

Label prediction was below confidence level 0.6 for Model:ServiceLabels: 'Azure.Core:0.56599855,Azure.Identity:0.18130244,Service Bus:0.10542601'

[xiangyan99]

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