update mui and conversations packages

[olipyskoty]

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Pull Request Details

JIRA link(s):

• N/A

Description

This PR addresses the bug reported in GitHub issue #552. This PR updates Material-UI to version 4.12.3 and Twilio Conversations to 1.2.3. These updates fix errors that users were experiencing when installing this app's packages, and using the quick deploy feature.

Burndown

Before review

• Updated CHANGELOG.md if necessary
• Added unit tests if necessary
• Updated affected documentation
• Verified locally with npm test
• Manually sanity tested running locally
• Included screenshot as PR comment (if needed)
• Ready for review

Before merge

• Got one or more +1s
• Re-tested if necessary