Implement version pinning

[sphr2k]

It would be great if we could pin versions for apps such as terraform, kubectl or istioctl, where often, it is not desirable to install the latest version.

[marcosnils]

good idea, and I also thing it's useful. I'll craft something this week

[peterwwillis]

Hi @marcosnils , I think I have some time to work on this now :D Have you done any work on this yet?

[marcosnils]

haven't done any progress unfortunately. Feel free to give it a try. LMK if you need any input from my side 🙏

[snwzd]

Hi @marcosnils, I've put together a simple implementation of version pinning on my fork. Where can I improve? (After that I'll make a PR)

[marcosnils]

Hey @snwzt, thx for sharing! I'd go ahead and open a PR as-is so we can start the conversations there. You can open the PR in draft mode also to emphasize that it's not review ready.