Support downloading directly from branch

[DannyBen]

Hello,

Since I found eget, it is my preferred installation mode, so first of all - thanks for the time you invest in it.

I am sure this was suggested or considered before, but I could not find it, so here goes:

Why not allow downloading from repos without a release? Intuitively, I tried:

eget dannyben/nlc/nlc   # download the nlc file from the repo

This could be extremely useful for repositories with simple scripts that provide "non binary" (no pun intended) downloads, so there is no need for a per-platform binary release.

An interesting anecdote - I spent the past 20 minutes chatting with ChatGPT which was absolutely certain that this is possible with all sorts of syntax options, like eget user/repo --branch master and other hallucinated (?) responses.