github tools: add fossa license scanning

[netlify-bot]

NOTICE: If this pull request does not apply to your repository, feel free to close this pull request. This is a generated pull request by github-tools to add Fossa license scanning to this repository.

You can check the status of your scan at https://app.fossa.com/projects/custom%2B17679%2Fgit%40github.com%3Anetlify%2FYOUR_PROJECT.git (replace YOUR_PROJECT with the name of your repository). If you have any questions or issues related to this (or if you are unable to access the Fossa report), please contact us on slack at #crew-internal-tools. The Fossa status check will fail until some code has been added to your master branch. The github action only runs upon merge to master so a scan report won't exist in the Fossa dashboard until this PR is merged in.

To add the license status as a badge on your README copy the following and replace YOUR_PROJECT with the name of your repository:

[![FOSSA Status](https://app.fossa.com/api/projects/custom%2B17679%2Fgit%40github.com%3Anetlify%2FYOUR_PROJECT.git.svg?type=shield)](https://app.fossa.com/projects/custom%2B17679%2Fgit%40github.com%3Anetlify%2FYOUR_PROJECT.git?ref=badge_shield)