[Security] Bump mixin-deep from 1.3.1 to 1.3.2

Bumps [mixin-deep](https://github.com/jonschlinkert/mixin-deep) from 1.3.1 to 1.3.2. **This update includes a security fix.**
- [Release notes](https://github.com/jonschlinkert/mixin-deep/releases)
- [Commits](jonschlinkert/mixin-deep@1.3.1...1.3.2)

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