Update Slack Invitation

[andreyvelich]

I updated Slack invitation for Training Operator Slack channel.

/assign @kubeflow/wg-training-leads

[google-oss-prow[bot]]

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[coveralls]

Pull Request Test Coverage Report for Build 9464768123

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.07%) to 35.423%

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Totals
Change from base Build 9323154860:	0.07%
Covered Lines:	4380
Relevant Lines:	12365

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💛 - Coveralls