fix(deps): Resolve React version incompatibility (#921)

The application was crashing on startup with a `ContextRegistry` error.
This was caused by the Gatsby v5 project inheriting an incompatible
version of React (v19) from the parent repository.

This change pins `react` and `react-dom` to `^18.2.0` in the
`package.json` to ensure compatibility with Gatsby and isolate its
environment.

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### Description

> Describe the purpose of this PR along with any background information
and the impacts of the proposed change. For the benefit of the
community, please do not assume prior context.
>
> Provide details that support your chosen implementation, including:
breaking changes, alternatives considered, changes to the API, etc.
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> If the UI is being changed, please provide screenshots.


### References

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> - GitHub Issue/PR number addressed or fixed
> - Auth0 Community post
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### Testing

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- [ ] This change adds test coverage for new/changed/fixed functionality

### Checklist

- [ ] I have added documentation for new/changed functionality in this
PR or in auth0.com/docs
- [ ] All active GitHub checks for tests, formatting, and security are
passing
- [ ] The correct base branch is being used, if not the default branch

Author: yogeshchoudhary147

examples/gatsby-app/package.json

@@ -7,8 +7,8 @@
     "@auth0/auth0-react": "file:../..",
     "bootstrap": "^5.0.0",
     "gatsby": "^5.0.1",
-    "react": "file:../../node_modules/react",
-    "react-dom": "file:../../node_modules/react-dom"
+    "react": "^18.2.0",
+    "react-dom": "^18.2.0"
   },
   "devDependencies": {
     "prettier": "2.0.5",