Bump loader-utils and gatsby-plugin-netlify-cms

Bumps [loader-utils](https://github.com/webpack/loader-utils) to 1.4.2 and updates ancestor dependency [gatsby-plugin-netlify-cms](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-netlify-cms). These dependencies need to be updated together.


Updates `loader-utils` from 1.2.3 to 1.4.2
- [Release notes](https://github.com/webpack/loader-utils/releases)
- [Changelog](https://github.com/webpack/loader-utils/blob/v1.4.2/CHANGELOG.md)
- [Commits](webpack/loader-utils@v1.2.3...v1.4.2)

Updates `gatsby-plugin-netlify-cms` from 4.1.6 to 7.0.0
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-netlify-cms/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/[email protected]/packages/gatsby-plugin-netlify-cms)

---
updated-dependencies:
- dependency-name: loader-utils
  dependency-type: indirect
- dependency-name: gatsby-plugin-netlify-cms
  dependency-type: direct:production
...

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