fix(download_lt): set default version to latest release

[mdevolde]

fix(download_lt): set default version to latest release

Why the pull request was made

In the continuity of the previous changes, the default version is put back on the latest stable release (6.8) which is now downloadable, and no longer the snapshots. It also allows you to benefit from the hash check that has been implemented for releases.

Summary of changes

• Set default LT version to release 6.8.
• Downloading the latest snapshot will now rename the snapshot as the other snapshots (with the snapshot day), and not anymore with the future release name (eg. LanguageTool-6.9-SNAPSHOT). So, by setting "latest" in download version, it will download the latest snapshot each day of use (so, the only way to have a stable version is to use a release/archive, as before).
• Added related tests.

Screenshots (if appropriate):

Not applicable.

How has this been tested?

Applied local tests.

Resources

Not applicable.

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)
• Documentation update (changes to documentation only)
• Refactor / code style update (non-breaking change that improves code structure or readability)
• Tests / CI improvement (adding or updating tests or CI configuration only)
• Other (please describe): fix the default version of downloaded LT

Checklist

• Followed the project's contributing guidelines.
• Updated any relevant tests.
• Updated any relevant documentation.
• Added comments to your code where necessary.
• Formatted your code, run the linters, checked types and tests.