seeli: unbind the chalk functions

binding breaks the chainable builder functionality.
now you can do `seeli.blue.dim('test')`

Semver: patch

lib/index.js

@@ -107,7 +107,7 @@ module.exports = {
 };
 
 colors.forEach(( color ) => {
-  module.exports[color] = chalk[color].bind( chalk );
+  module.exports[color] = chalk[color]
 });
 
 Object.defineProperties( module.exports, {