Bump eslint

Bumps the twentytwentyone-eslint group in /src/wp-content/themes/twentytwentyone with 1 update: [eslint](https://github.com/eslint/eslint).


Updates `eslint` from 8.57.1 to 9.39.1
- [Release notes](https://github.com/eslint/eslint/releases)
- [Commits](eslint/eslint@v8.57.1...v9.39.1)

---
updated-dependencies:
- dependency-name: eslint
  dependency-version: 9.39.1
  dependency-type: direct:development
  update-type: version-update:semver-major
  dependency-group: twentytwentyone-eslint
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]