In bash (and other shells), the leading `$` in `$VERSION=stable` will fail.
The correct variable assignment looks like:

```sh
VERSION=stable
```

Furthermore, if `VERSION` is stable, the directory will not be
called `likwid-stable`  but (at the moment) will be `likwid-5.2.0`.
A workaround is to simply use an `*` as that will be substituted
by the the correct directory, assuming that only one
`likwid-xyz` directory exists.