Add `builders.tar.gz` to pkg "assets" configuration (#2541)
Add `builders.tar.gz` to pkg "assets" configuration (#2541)

Fixes this error from the pkg'd binary:

```
Error: File or directory '/**/now-cli/dist/builders.tar.gz'
was not included into executable at compilation stage.
Please recompile adding it as asset or script.
```
zeit/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli