Upgrade packages and fix linter

[timmydoza]

Contributing to Twilio

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• I acknowledge that all my contributions will be made under the project's license.

Pull Request Details

JIRA link(s):

• N/A

Description

• Upgraded twilio-video.js to 2.12.0
• Upgraded react-scripts from version 4.0.2 to 4.0.3 (to fix an issue with the linter)
• Upgrade ts-jest from 24.3.0 to 26.5.1 (to match the version of jest installed by react-scripts)
• Fixed the script for npm run lint so that it is able to lint all files
• Fixed all warnings and errors reported by linter

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

[olipyskoty]

I see one more warning when i run npx eslint src:
.../twilio-video-app-react/src/types.ts 6:13 warning 'LocalVideoTrack' is already declared in the upper scope on line 1 column 10

not sure if you saw that too, or if that warning can be ignored but thought I would point it out. Otherwise, looks good!

[timmydoza]

Updated PR to add Eslint step to CircleCI pipeline:

[timmydoza]

I see one more warning when i run npx eslint src:
.../twilio-video-app-react/src/types.ts 6:13 warning 'LocalVideoTrack' is already declared in the upper scope on line 1 column 10

not sure if you saw that too, or if that warning can be ignored but thought I would point it out. Otherwise, looks good!

I'm not seeing that one on my side. This made me realize that there was no Eslint step in the CircleCI pipeline, so I added it. Looks like it isn't showing up there either.