Bump cross-fetch, @ampproject/toolbox-core and @ampproject/toolbox-va…

…lidator-rules

Bumps [cross-fetch](https://github.com/lquixada/cross-fetch), [@ampproject/toolbox-core](https://github.com/ampproject/amp-toolbox/tree/HEAD/packages/core) and [@ampproject/toolbox-validator-rules](https://github.com/ampproject/amp-toolbox/tree/HEAD/packages/validator-rules). These dependencies needed to be updated together.

Updates `cross-fetch` from 3.0.4 to 3.1.5
- [Release notes](https://github.com/lquixada/cross-fetch/releases)
- [Commits](lquixada/cross-fetch@v3.0.4...v3.1.5)

Updates `@ampproject/toolbox-core` from 2.3.0 to 2.9.0
- [Release notes](https://github.com/ampproject/amp-toolbox/releases)
- [Changelog](https://github.com/ampproject/amp-toolbox/blob/main/CHANGELOG.md)
- [Commits](https://github.com/ampproject/amp-toolbox/commits/v2.9.0/packages/core)

Updates `@ampproject/toolbox-validator-rules` from 2.3.0 to 2.9.0
- [Release notes](https://github.com/ampproject/amp-toolbox/releases)
- [Changelog](https://github.com/ampproject/amp-toolbox/blob/main/CHANGELOG.md)
- [Commits](https://github.com/ampproject/amp-toolbox/commits/v2.9.0/packages/validator-rules)

---
updated-dependencies:
- dependency-name: cross-fetch
  dependency-type: indirect
- dependency-name: "@ampproject/toolbox-core"
  dependency-type: indirect
- dependency-name: "@ampproject/toolbox-validator-rules"
  dependency-type: indirect
...

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