Update CHANGELOG.md

Author: justinmerrell

CHANGELOG.md

@@ -1,5 +1,18 @@
 # Change Log
 
+## Release 1.5.2 (1/16/24)
+
+### Fixed
+
+- Edge case when using RunPod Serverless Core that return `None` for function output.
+- Missing Job ID for logging.
+- Concurrency modifier not adhering to the maximum concurrency.
+- Improved in progress job tracking and counting.
+
+### Added
+
+- Expanded RunPod Serverless Core testing.
+
 ## Release 1.5.1 (1/11/24)
 
 ### Fixed