Bump gatsby-plugin-material-ui from 1.2.5 to 4.1.0

Bumps [gatsby-plugin-material-ui](https://github.com/hupe1980/gatsby-plugin-material-ui) from 1.2.5 to 4.1.0.
- [Release notes](https://github.com/hupe1980/gatsby-plugin-material-ui/releases)
- [Commits](hupe1980/gatsby-plugin-material-ui@v1.2.5...v4.1.0)

---
updated-dependencies:
- dependency-name: gatsby-plugin-material-ui
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]