vim: Use EN instead of EN_US dict for spell check

I do not care about color/colour etc.

.config/vim/ftplugin/gitcommit.vim

@@ -1,4 +1,4 @@
 " Shorter lines. Subject should be max 50 and body max 72
 setlocal colorcolumn=50,72
 " Spell checking always enabled
-setlocal spell spelllang=en_us
+setlocal spell spelllang=en

.config/vim/vimrc

@@ -28,7 +28,7 @@ set undofile
 " Update every 300ms for better experience with plugins like gitgutter and coc
 set updatetime=300
 " Check for spelling in comments and strings
-set spell spelllang=en_us
+set spell spelllang=en
 " Show the effect of a command while typing (substitute)
 if (has('nvim'))
 	set inccommand=nosplit