Bump socket.io-parser and gatsby in /docs (#278)

Bumps [socket.io-parser](https://github.com/socketio/socket.io-parser) to 4.2.3 and updates ancestor dependency [gatsby](https://github.com/gatsbyjs/gatsby). These dependencies need to be updated together.


Updates `socket.io-parser` from 4.0.5 to 4.2.3
- [Release notes](https://github.com/socketio/socket.io-parser/releases)
- [Changelog](https://github.com/socketio/socket.io-parser/blob/main/CHANGELOG.md)
- [Commits](socketio/socket.io-parser@4.0.5...4.2.3)

Updates `gatsby` from 4.25.1 to 4.25.7
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/compare/gatsby@4.25.1...gatsby@4.25.7)

---
updated-dependencies:
- dependency-name: socket.io-parser
  dependency-type: indirect
- dependency-name: gatsby
  dependency-type: direct:production
...

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Author: dependabot[bot]