fix but when mentioning a slack user in summary

Author: arikalon1

src/robusta/integrations/slack/sender.py

@@ -2,6 +2,7 @@
 import logging
 import ssl
 import tempfile
+import re
 from datetime import datetime, timedelta
 from itertools import chain
 from typing import Any, Dict, List, Optional, Set
@@ -52,6 +53,7 @@
 ACTION_LINK = "link"
 SlackBlock = Dict[str, Any]
 MAX_BLOCK_CHARS = 3000
+MENTION_PATTERN = re.compile(r"<[^>]+>")
 
 
 class SlackSender:
@@ -410,8 +412,12 @@ def __create_holmes_callback(self, finding: Finding) -> CallbackBlock:
     def __create_finding_header(
         self, finding: Finding, status: FindingStatus, platform_enabled: bool, include_investigate_link: bool
     ) -> MarkdownBlock:
-        title = (finding.title.removeprefix("[RESOLVED] ")
-                 .replace("<", "&lt;").replace(">", "&gt;"))
+        title = finding.title.removeprefix("[RESOLVED] ")
+
+        match = MENTION_PATTERN.search(title)
+        mention = f" {match.group(0)}" if match else ""
+        title = MENTION_PATTERN.sub("", title).strip()
+
         sev = finding.severity
         if finding.source == FindingSource.PROMETHEUS:
             status_name: str = (
@@ -427,7 +433,7 @@ def __create_finding_header(
             title = f"<{finding.get_investigate_uri(self.account_id, self.cluster_name)}|*{title}*>"
         return MarkdownBlock(
             f"""{status_name} {sev.to_emoji()} *{sev.name.capitalize()}*
-{title}"""
+{title}{mention}"""
         )
 
     def __create_links(