Update NEXT_CHANGELOG.md with bug fix and internal change entries

Author: Nepomuk5665

NEXT_CHANGELOG.md

@@ -7,10 +7,12 @@
 ### New Features and Improvements
 
 ### Bug Fixes
+* Fix potential panic in `shouldRetry` function by using comma-ok idiom for type assertion ([#1438](https://github.com/databricks/databricks-sdk-go/pull/1438)).
 
 ### Documentation
 
 ### Internal Changes
+* Remove deprecated `rand.Seed` call in retry backoff logic ([#1438](https://github.com/databricks/databricks-sdk-go/pull/1438)).
 
 ### API Changes
 * Add `Force` field for [pipelines.DeletePipelineRequest](https://pkg.go.dev/github.com/databricks/databricks-sdk-go/service/pipelines#DeletePipelineRequest).