Edit changelog for version 2.13

Changelog.md

 # Changelog
 
+## [2.13] - 2024-09-18
+- Run cleanup at 1 AM only, not every minute between 1 and 2 AM.
+- Add checklist to trunk migration and include ACTIVITY_TYPE column as discussed with SM.
+- Fix SDP update logic in the promotion from P to PE.
+- Update core lib to 2.7.4
+- Refactor validators into a separate types module.
+- Add Tier3 model for Netbox.
+- Fix: Increase initial connection timeout for LibreNMS client.
+- Fix: Change type from LAGMember to dict for workflow step in trunk modification
+- Make celery concurrency level to 1
+
 ## [2.12] - 2024-08-22
 - Add promote P to PE workflow.
 - Add new cleanup task