no `ggsql.vsix` to download

[espinielli]

In the installation page [1] the link for ggsql.vsix points to no file to download.

[1] https://ggsql.org/get_started/installation.html#vs-code-positron-extension

[espinielli]

It is instead available on open-vsx.org at
https://open-vsx.org/api/ggsql/ggsql/0.2.7/file/ggsql.ggsql-0.2.7.vsix

[thomasp85]

Related to #328 - I think we will drop the link completely

[teunbrand]

Closing as duplicate as the solution would be the same