sat solver: nimble reinstalls dependencies from git repositories each rebuild
nimble reinstalls depenciencies from git repositories links each rebuild making each recompile slower.
this doesn't occur in `--solver:legacy` only with new `--solver:sat`
easy reproduce:
```nim
# Package
requires "nim >= 2.2.2"
requires "nimPNG" # this will not be reinstalled each rebuild so it's fine
requires "https://github.com/mrgaturus/nogui#head" # this will be reinstalled each rebuild
```

nimble version (the one shipped with new nim 2.2.2)
```
nimble v0.16.4 compiled at 2025-02-06 02:02:41
git hash: couldn't determine git hash
```