Fix the type error causing build failure in the destination package

[mia-mifeng]

Description

This PR fixes the error A computed property name in an interface must refer to an expression whose type is a literal type or a 'unique symbol' type. described in the issue #272. See "possible solution" in the issue for more details.

Related Issue

#272

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

🎨 Storybook -> https://opensource.adobe.com/react-spectrum-charts/PR-270