Upgrade doorstop to version 4.2.0 (v6)

[aldelaro5]

Description

This upgrades bepinex (master) to use Doorstop version 4.2.0 with equivalent defaults regarding the mono search paths changes

Motivation and Context

It fixes minor issues and improves the flexibility regarding the mono search path.

How Has This Been Tested?

I haven't tested much besides the fact that it compiles (I am not familiar with v6 enough)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.