Fix tests

[benoit74]

Tests are not working, with following error:

> npm run test
(node:2143) ExperimentalWarning: VM Modules is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for /home/runner/work/phet/phet/steps/setup.ts
    at new NodeError (node:internal/errors:405:5)
    at Object.getFileProtocolModuleFormat [as file:] (node:internal/modules/esm/get_format:136:11)
    at defaultGetFormat (node:internal/modules/esm/get_format:182:36)
    at defaultLoad (node:internal/modules/esm/load:101:20)
    at nextLoad (node:internal/modules/esm/hooks:864:28)
    at load (/home/runner/work/phet/phet/node_modules/ts-node/dist/child/child-loader.js:19:122)
    at nextLoad (node:internal/modules/esm/hooks:864:28)
    at Hooks.load (node:internal/modules/esm/hooks:447:26)
    at MessagePort.handleMessage (node:internal/modules/esm/worker:196:24)
    at [nodejs.internal.kHybridDispatch] (node:internal/event_target:786:20) {
  code: 'ERR_UNKNOWN_FILE_EXTENSION'
}

They have been remove from CI for now, to be put back in place