Make CompatibilityCollector able to parse a single version String

[bergmeister]

PR Summary

Make CompatibilityCollector able to parse a single version String.
I found it odd that the version number is -1 when not being specified (System.Management.Automation.SemanticVersion uses a 0 in that case) but I tried to be at least consistent with the current implementation...

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Change is not breaking
• Make sure all .cs, .ps1 and .psm1 files have the correct copyright header
• Make sure you've added a new test if existing tests do not effectively test the code changed and/or updated documentation
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: to the beginning of the title and remove the prefix when the PR is ready.

[rjmholt]

Thanks for this @bergmeister!

[bergmeister]

You're welcome, it was a relatively easy fix