use base0A for brace_good in dark themes in Geany

This commit changes the color for  `brace_good` in https://github.com/chriskempson/base16-builder/blob/master/templates/geany/dark.conf.erb from  `base0B`  to  `base0A`. This improves contrast, thus allows for much easier spotting and following of braces. 

This change was already discussed here: 
https://github.com/RobLoach/base16-geany/issues/7