npm(deps): bump mobx from 6.15.3 to 6.16.1

Bumps [mobx](https://github.com/mobxjs/mobx) from 6.15.3 to 6.16.1.
- [Release notes](https://github.com/mobxjs/mobx/releases)
- [Commits](https://github.com/mobxjs/mobx/compare/mobx@6.15.3...mobx@6.16.1)

---
updated-dependencies:
- dependency-name: mobx
  dependency-version: 6.16.1
  dependency-type: indirect
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]