Fastlane: CVE-2019-13574 in fastlane dependency.

[mijoharas]

New Issue Checklist

• [x] Updated fastlane to the latest version
• [x] I read the Contribution Guidelines
• [x] I read docs.fastlane.tools
• [x] I searched for existing GitHub issues

Issue Description

Fastlane uses mini_magick '~> 4.5.1' which suffers from CVE-2019-13574.

Solution

Upgrade the mini_magick dependency to >= 4.9.4

[rmtheis]

https://github.com/fastlane/fastlane/pull/15042