Bump tough-cookie and less in /_site

Removes [tough-cookie](https://github.com/salesforce/tough-cookie). It's no longer used after updating ancestor dependency [less](https://github.com/less/less.js). These dependencies need to be updated together.


Removes `tough-cookie`

Updates `less` from 3.11.1 to 3.13.1
- [Release notes](https://github.com/less/less.js/releases)
- [Changelog](https://github.com/less/less.js/blob/master/CHANGELOG.md)
- [Commits](less/less.js@v3.11.1...v3.13.1)

---
updated-dependencies:
- dependency-name: tough-cookie
  dependency-type: indirect
- dependency-name: less
  dependency-type: indirect
...

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