Shake.yaml file not found

When building using stack:

```
stack ./install.hs hls
```

I get the following error:

```
# stack (for hls-8.8.3)
Could not parse '/Users/nicola/3rdParty/haskell-language-server/install/shake.yaml':
YAML exception:
Yaml file not found: /Users/nicola/3rdParty/haskell-language-server/install/shake.yaml
See http://docs.haskellstack.org/en/stable/yaml_configuration/
```
