docker run: invalid reference format

Operating system: mac 

**Issue**
```
docker run -v $(pwd):/project ruudboon/phalcon-rector:php73-v3_to_v4
docker: invalid reference format: repository name must be lowercase.
See 'docker run --help'.
```

**Solution**
`docker run -v "$(pwd):/project" ruudboon/phalcon-rector:php73-v3_to_v4`
wrapping `$(pwd):/project` in "" solves the issue. 


