Migrated from yarn to pnpm

[david-yz-liu]

Proposed Changes

(Describe your changes here. Also describe the motivation for your changes: what problem do they solve, or how do they improve the application or codebase? If this pull request fixes an open issue, use a keyword to link this pull request to the issue.)

This PR migrates the Javascript package manager from yarn to pnpm.

Screenshots of your changes (if applicable)

Type of Change

(Write an X or a brief description next to the type or types that best describe your changes.)

Type	Applies?
🚨 Breaking change (fix or feature that would cause existing functionality to change)
✨ New feature (non-breaking change that adds functionality)
🐛 Bug fix (non-breaking change that fixes an issue)
🎨 User interface change (change to user interface; provide screenshots)
♻️ Refactoring (internal change to codebase, without changing functionality)
🚦 Test update (change that only adds or modifies tests)
📦 Dependency update (change that updates a dependency)
🔧 Internal (change that only affects developers or continuous integration)

Checklist

(Complete each of the following items for your pull request. Indicate that you have completed an item by changing the [ ] into a [x] in the raw text, or by clicking on the checkbox in the rendered description on GitHub.)

Before opening your pull request:

• I have performed a self-review of my changes.
  • Check that all changed files included in this pull request are intentional changes.
  • Check that all changes are relevant to the purpose of this pull request, as described above.
• I have added tests for my changes, if applicable.
  • This is required for all bug fixes and new features.
• I have updated the project documentation, if applicable.
  • This is required for new features.
• If this is my first contribution, I have added myself to the list of contributors.
• I have updated the project Changelog (this is required for all changes).

After opening your pull request:

• I have verified that the CircleCI checks have passed.
• I have requested a review from a project maintainer.

Questions and Comments

(Include any questions or comments you have regarding your changes.)

[coveralls]

Coverage Report for CI Build 25559258

Coverage remained the same at 58.696%

Details

• Coverage remained the same as the base build.
• Patch coverage: No coverable lines changed in this PR.
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	4359
Covered Lines:	2612
Line Coverage:	59.92%
Relevant Branches:	1011
Covered Branches:	540
Branch Coverage:	53.41%
Branches in Coverage %:	Yes
Coverage Strength:	153.69 hits per line

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💛 - Coveralls