move from `importAssertions` to `importAttributes`

[kentcdodds]

Summary

This is to account for the change in the proposal: https://github.com/tc39/proposal-import-attributes

Without this, you'll get the following warning on recent versions of node:

(node:39166) ExperimentalWarning: Use `importAttributes` instead of `importAssertions`

How did you test this change?

Did a find/replace and ran the tests. I also use the react-server-dom-esm node loader in a workshop with Node v20.10.0 and this change removed the warning while preserving the functionality. I did not test the other packages.

[react-sizebot]

Comparing: 190cc990e01e5131a6b26f1a3212444cebd794e2...8c68a19de0554fb0754c1c1e38e52d346b19d109

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.js	=	6.66 kB	6.66 kB	=	1.82 kB	1.82 kB
oss-experimental/react-dom/cjs/react-dom.production.js	=	6.67 kB	6.67 kB	=	1.83 kB	1.83 kB
facebook-www/ReactDOM-prod.classic.js	=	591.11 kB	591.11 kB	=	103.94 kB	103.94 kB
facebook-www/ReactDOM-prod.modern.js	=	567.33 kB	567.33 kB	=	100.34 kB	100.34 kB
test_utils/ReactAllWarnings.js	Deleted	64.26 kB	0.00 kB	Deleted	16.02 kB	0.00 kB

Significant size changes

Includes any change greater than 0.2%:

Expand to show

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
test_utils/ReactAllWarnings.js	Deleted	64.26 kB	0.00 kB	Deleted	16.02 kB	0.00 kB

Generated by :no_entry_sign: dangerJS against 8c68a19de0554fb0754c1c1e38e52d346b19d109

[github-actions[bot]]

This pull request has been automatically marked as stale. If this pull request is still relevant, please leave any comment (for example, "bump"), and we'll keep it open. We are sorry that we haven't been able to prioritize reviewing it yet. Your contribution is very much appreciated.

[kentcdodds]

It's not very important, but it's also very simple. A merge would be appreciated!