Make cygwinMSYSCheck more robust (#186)

[RyanGlScott]

We cannot rely on "-master" being at the end of the filepath name in cygwinMSYSCheck on recent MinTTYs.

Description

To accommodate, this patch updates the implementation of cygwinMSYSCheck to match what git-for-windows does:

• Always use isInfixOf to check if "cygwin-", "msys-", and "-pty" are in the filepath name.
• Don't check "-master" at all, as this seems to assume a naming convention that could change in the future.

Motivation and Context

Fixes #186.

Types of changes

• [x] 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 change)

Checklist:

• [x] My code follows the code style of this project.
• [x] I have updated the documentation accordingly.
• [x] I have not added a new Haskell dependency.
• [x] I have included a changelog entry.
• [x] I have not modified the version of the package in Win32.cabal.

[Mistuke]

Thanks! Ugh did someone move the 32-bit cabal..

[Mistuke]

Hmm looks like a CDN issue likely.

[Mistuke]

Thanks, looks good, I'll merge and release tomorrow when Im behind a computer.