Bump styled-components from 5.3.11 to 6.0.2 in /cmd/mdl/webapp

Bumps [styled-components](https://github.com/styled-components/styled-components) from 5.3.11 to 6.0.2.
- [Release notes](https://github.com/styled-components/styled-components/releases)
- [Commits](styled-components/styled-components@v5.3.11...v6.0.2)

---
updated-dependencies:
- dependency-name: styled-components
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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