[BUG] gitgutter: Signs are displayed in white

[werdahias]

Describe the bug

1. with vgitgutter enable the diff signs still show up, but they are not colored as before (i.e. changed / ~ in blue, deleted / - in red , added / + in green

Expected behaviour

I'd expect that the gitgutter signs are colored

Screenshots

[werdahias]

likely fixed by #385