Switch just names to "Constant" syntax group

for better visibility/differentiation

vim-just/syntax/just.vim

@@ -120,8 +120,8 @@ syn region justSubshell matchgroup=justBacktick start="\v\`\`\`" skip="\v\\\`" e
 syn region justRecipeBody start="\v^  *" end="$" keepend contains=@setshellsyntax
 syn region justRecipeNoechoBody start="\v^  *\@" end="$" keepend contains=justOperator,@setshellsyntax
 
-hi def link justPublicName Identifier
-hi def link justPrivateName Identifier
+hi def link justPublicName Constant
+hi def link justPrivateName Constant
 hi def link justKeyword Keyword
 hi def link justSetting Keyword
 hi def link justOperator Operator