add :simple_smile: to 😄 emoji for Slack compatibility

lib/rumoji/emoji/people.rb

@@ -6,7 +6,7 @@ require 'set'
 module Rumoji
 module Rumoji
   class Emoji
   class Emoji
     PEOPLE = Set[
     PEOPLE = Set[
-      self.new("\u{1F604}", [:smile], "SMILING FACE WITH OPEN MOUTH AND SMILING EYES"),
+      self.new("\u{1F604}", [:smile, :simple_smile], "SMILING FACE WITH OPEN MOUTH AND SMILING EYES"),
       self.new("\u{1F606}", [:laughing], "SMILING FACE WITH OPEN MOUTH AND TIGHTLY-CLOSED EYES"),
       self.new("\u{1F606}", [:laughing], "SMILING FACE WITH OPEN MOUTH AND TIGHTLY-CLOSED EYES"),
       self.new("\u{1F60A}", [:blush], "SMILING FACE WITH SMILING EYES"),
       self.new("\u{1F60A}", [:blush], "SMILING FACE WITH SMILING EYES"),
       self.new("\u{1F603}", [:smiley], "SMILING FACE WITH OPEN MOUTH"),
       self.new("\u{1F603}", [:smiley], "SMILING FACE WITH OPEN MOUTH"),