Bump eta, @docusaurus/core and @docusaurus/preset-classic in /docs

Bumps [eta](https://github.com/eta-dev/eta) to 2.0.1 and updates ancestor dependencies [eta](https://github.com/eta-dev/eta), [@docusaurus/core](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus) and [@docusaurus/preset-classic](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus-preset-classic). These dependencies need to be updated together.


Updates `eta` from 1.12.3 to 2.0.1
- [Release notes](https://github.com/eta-dev/eta/releases)
- [Commits](eta-dev/eta@v1.12.3...v2.0.1)

Updates `@docusaurus/core` from 2.2.0 to 2.4.0
- [Release notes](https://github.com/facebook/docusaurus/releases)
- [Changelog](https://github.com/facebook/docusaurus/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/docusaurus/commits/v2.4.0/packages/docusaurus)

Updates `@docusaurus/preset-classic` from 2.2.0 to 2.4.0
- [Release notes](https://github.com/facebook/docusaurus/releases)
- [Changelog](https://github.com/facebook/docusaurus/blob/main/CHANGELOG.md)
- [Commits](https://github.com/facebook/docusaurus/commits/v2.4.0/packages/docusaurus-preset-classic)

---
updated-dependencies:
- dependency-name: eta
  dependency-type: indirect
- dependency-name: "@docusaurus/core"
  dependency-type: direct:production
- dependency-name: "@docusaurus/preset-classic"
  dependency-type: direct:production
...

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