bug #3030 [React] Fix importmap to require react-dom/client (Kocal)

This PR was merged into the 2.x branch.

Discussion
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[React] Fix importmap to require `react-dom/client`

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Docs?         | no <!-- required for new features -->
| Issues        | Fix #... <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT

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Following #2944, where the code changed from `import require$$0 from 'react-dom';` to `import { createRoot } from "react-dom/client";`.

I forgot to update the `importmap` entry and add `react-dom/client` dependency.

Commits
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e41b4ed [React] Fix importmap to require `react-dom/client`

Author: Kocal

src/React/assets/package.json

@@ -35,7 +35,7 @@
         "importmap": {
             "@hotwired/stimulus": "^3.0.0",
             "react": "^18.0",
-            "react-dom": "^18.0",
+            "react-dom/client": "^18.0",
             "@symfony/ux-react": "path:%PACKAGE%/dist/loader.js"
         }
     },