[React] A warning appears when building `defaultV2.css`

[JaneSjs]

T16448 - Getting error during npm run build - React CRA
https://surveyjs.answerdesk.io/internal/ticket/details/T16448

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To reproduce the issue, run this demo, install npm packages and run npm start. The following warning appears in a console:
my-ts-app.zip

./node_modules/survey-core/defaultV2.min.css (./node_modules/css-loader/dist/cjs.js??ref--6-oneOf-3-1!./node_modules/postcss-loader/src??postcss!./node_modules/survey-core/defaultV2.min.css)
Warning

(6:32638) start value has mixed support, consider using flex-start instead