make default config DB_USERNAME 'root'

Author: Naoray

lambo

@@ -179,7 +179,7 @@ AUTH=false
 NODE=false
 CODEEDITOR=""
 BROWSER=""
-DB_USERNAME=""
+DB_USERNAME="root"
 DB_PASSWORD=""
 if [[ -f ~/.config/valet/config.json ]]; then
     TLD=$(php -r "echo json_decode(file_get_contents('$HOME/.config/valet/config.json'))->tld;")