Add gut-extensions to Open VSX

[graugraugrau]

For users of Code - OSS or VS Codium it's not possible to install this extension from the marketplace without workarounds. If this extension would be available in Open VSX, users of these IDEs could also use it. Hence more people could use your extension.

See also:

• https://open-vsx.org/
• https://wiki.archlinux.org/title/Visual_Studio_Code#Extensions_support