Bump mithril from 1.1.6 to 1.1.7

Bumps [mithril](https://github.com/MithrilJS/mithril.js) from 1.1.6 to 1.1.7.
- [Release notes](https://github.com/MithrilJS/mithril.js/releases)
- [Changelog](https://github.com/MithrilJS/mithril.js/blob/next/docs/changelog.md)
- [Commits](MithrilJS/mithril.js@v1.1.6...v1.1.7)

---
updated-dependencies:
- dependency-name: mithril
  dependency-type: direct:production
...

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Author: dependabot[bot]