Remove ThreadColor

Replaced with raw color values. In the future, we should probably
investigate using "themes"

examples/interract.py

@@ -54,8 +54,8 @@ thread.set_nickname(fbchat.User(session=session, id="<user id>"), "<new nickname
 # Will set the typing status of the thread
 thread.start_typing()
 
-# Will change the thread color to `MESSENGER_BLUE`
-thread.set_color(fbchat.ThreadColor.MESSENGER_BLUE)
+# Will change the thread color to #0084ff
+thread.set_color("#0084ff")
 
 # Will change the thread emoji to `👍`
 thread.set_emoji("👍")

examples/keepbot.py

@@ -4,7 +4,7 @@ import fbchat
 old_thread_id = "1234567890"
 
 # Change these to match your liking
-old_color = fbchat.ThreadColor.MESSENGER_BLUE
+old_color = "#0084ff"
 old_emoji = "👍"
 old_title = "Old group chat name"
 old_nicknames = {