Fixes warnings on SBT startup
```
$ sbt
[info] welcome to sbt 1.9.0 (GraalVM Community Java 17.0.7)
...
[warn] 5 feature warnings; re-run with -feature for details
[warn] one warning found
[info] loading settings for project enso from build.sbt ...
```
1. This commit ensures that builds outside of repository don't file not being
able to fetch the git metadata for the version string but just report a
warning.
2. It also clarifies documentation on getting Enso artifacts from CI.
PR #1036