(librecad) Switch to using new GitHub API helper

[AdmiringWorm]

Description

This pull request updates the automatic updater to make use of our new GitHub API helper to get the releases available.
This allows this package to once again be pushed to Chocolatey Community Repository.

Additionally, a small change to include the already pushed versions of 2.1 and 2.0 has been added, without having these added and if we need to create a fix version we would first need to add these manually or explicitly set the version to use.

fixes #2194

Motivation and Context

To make the automatic updater work again.

How Has this Been Tested?

1. Run .\update_all.ps1 librecad
2. Verify a package was created for 2.2.0
3. Run .\update_all.ps1 librecad -ForcedPackages librecad\2.1
4. Verify a fix version for version 2.1.3 was created

Screenshot (if appropriate, usually isn't needed):

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 change)
• Migrated package (a package has been migrated from another repository)

Checklist:

• My code follows the code style of this repository.
• My change requires a change to documentation (this usually means the notes in the description of a package).
• I have updated the documentation accordingly (this usually means the notes in the description of a package).
• I have updated the package description and it is less than 4000 characters.
• All files are up to date with the latest Contributing Guidelines
• The added/modified package passed install/uninstall in the chocolatey test environment (only update.ps1 is affected here, so install/uninstall has not been checked).
• The changes only affect a single package (not including meta package).

[AppVeyorBot]

✅ Package verification completed without issues. PR is now pending human review

[JPRuskin]

LGTM!