remove v0.7.0 warning

[eitanturok]

Description of changes:

remove part of the warning messages about v0.7.0 of streaming.

Issue #, if available:

Merge Checklist:

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General

• [x] I have read the contributor guidelines
• [ ] This is a documentation change or typo fix. If so, skip the rest of this checklist.
• [x] I certify that the changes I am introducing will be backward compatible, and I have discussed concerns about this, if any, with the MosaicML team.
• [x] I have updated any necessary documentation, including README and API docs (if appropriate).

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• [ ] I have added tests that prove my fix is effective or that my feature works (if appropriate).
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• [ ] I have added unit and/or integration tests as appropriate to ensure backward compatibility of the changes.