PE-18486: Token Clean-up

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: CarloGiannattasio

tools/c7n_mailer/c7n_mailer/target.py

@@ -67,7 +67,7 @@ def handle_targets(self, message, sent_timestamp):
             from .slack_delivery import SlackDelivery
 
             slack_token: str = self.config.get("slack_token")
-            if slack_token and not slack_token.startswith("xoxb-"):
+            if slack_token:
                 slack_token = decrypt(self.config, self.logger, self.session, "slack_token")
                 self.config["slack_token"] = slack_token