Removal of XMPP support due to instability (#619)

README.md

@@ -96,7 +96,6 @@ The table below identifies the services this tool supports and some example serv
 | [Twitter](https://github.com/caronc/apprise/wiki/Notify_twitter) | twitter://  | (TCP) 443   | twitter://CKey/CSecret/AKey/ASecret<br/>twitter://user@CKey/CSecret/AKey/ASecret<br/>twitter://CKey/CSecret/AKey/ASecret/User1/User2/User2<br/>twitter://CKey/CSecret/AKey/ASecret?mode=tweet
 | [Twist](https://github.com/caronc/apprise/wiki/Notify_twist) | twist://  | (TCP) 443   | twist://pasword:login<br/>twist://password:login/#channel<br/>twist://password:login/#team:channel<br/>twist://password:login/#team:channel1/channel2/#team3:channel
 | [XBMC](https://github.com/caronc/apprise/wiki/Notify_xbmc) | xbmc:// or xbmcs://    | (TCP) 8080 or 443   | xbmc://hostname<br />xbmc://user@hostname<br />xbmc://user:password@hostname:port
-| [XMPP](https://github.com/caronc/apprise/wiki/Notify_xmpp) | xmpp:// or xmpps://    | (TCP) 5222 or 5223   | xmpp://user:password@hostname<br />xmpps://user:password@hostname:port?jid=user@hostname/resource<br/>xmpps://user:password@hostname/target@myhost, target2@myhost/resource
 | [Webex Teams (Cisco)](https://github.com/caronc/apprise/wiki/Notify_wxteams) | wxteams://  | (TCP) 443   | wxteams://Token
 | [Zulip Chat](https://github.com/caronc/apprise/wiki/Notify_zulip) | zulip://  | (TCP) 443   | zulip://botname@Organization/Token<br />zulip://botname@Organization/Token/Stream<br />zulip://botname@Organization/Token/Email
 

all-plugin-requirements.txt

@@ -5,9 +5,6 @@
 # Provides fcm:// and spush://
 cryptography
 
-# Provides xmpp:// support
-slixmpp; python_version >= '3.7'
-
 # Provides growl:// support
 gntp