Update CHANGELOG (#510)

Co-authored-by: dd-octo-sts[bot] <200755185+dd-octo-sts[bot]@users.noreply.github.com>

Author: dd-octo-sts[bot]

CHANGELOG.md

@@ -1,5 +1,18 @@
 # Changelog
 
+## 3.1.1 / 2026-04-06
+
+### Fixed
+* Add logic to replicate file content of Synthetics Tests with file uploads by @melkouri in https://github.com/DataDog/datadog-sync-cli/pull/477
+### Added
+* fix: include endpoint path in paginated request error log by @michael-richey in https://github.com/DataDog/datadog-sync-cli/pull/506
+
+## New Contributors
+* @hazrac made their first contribution in https://github.com/DataDog/datadog-sync-cli/pull/502
+* @gh-worker-campaigns-3e9aa4[bot] made their first contribution in https://github.com/DataDog/datadog-sync-cli/pull/505
+
+**Full Changelog**: https://github.com/DataDog/datadog-sync-cli/compare/3.1.0...3.1.1
+
 ## 3.1.0 / 2026-03-27
 
 ### Fixed