Suppress uninitialized instance variable warning
Suppress uninitialized instance variable warning

```
/home/pocke/.rbenv/versions/trunk/lib/ruby/gems/2.7.0/gems/itamae-1.10.3/lib/itamae/logger.rb:82: warning: instance variable (at)color not initialized
```

sue445/itamae,sue445/itamae,itamae-kitchen/itamae,itamae-kitchen/itamae