Bump gatsby from 2.29.1 to 4.25.7

Bumps [gatsby](https://github.com/gatsbyjs/gatsby) from 2.29.1 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/[email protected]@4.25.7)

---
updated-dependencies:
- dependency-name: gatsby
  dependency-type: direct:production
...

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

Author: dependabot[bot]