Remove mypy ignore for AzureBlobClient upload when azure-storage-blob is updated

[github-actions]

Workflow failed: tests #483

[jayqi]

This error appears to be a type annotation issue in azure-storage-blob. Azure/azure-sdk-for-python#23362

[jayqi]

PR #217 adds a mypy ignore comment to silence this error. The typing has been fixed in azure-blob-storage but won't be available until their next release. We should remove the ignore comment when that release is available.

Azure/azure-sdk-for-python#23362 (comment)