changelog finalization for beta.4 patch (#43767)

Author: trrwilson

sdk/openai/Azure.AI.OpenAI.Assistants/CHANGELOG.md

@@ -1,16 +1,15 @@
 # Release History
 
-## 1.0.0-beta.4 (Unreleased)
+## 1.0.0-beta.4 (2024-04-30)
 
-### Features Added
-
-### Breaking Changes
+This small, out-of-band version addresses a couple of critical blocking bugs. It does not yet include any of the latest
+features. Streaming support and Assistants v2 will come soon, in a future update.
 
 ### Bugs Fixed
 
 - Several issues with direct equality comparisons of function tool definitions have been fixed
-
-### Other Changes
+- The mistaken, remain instance of an "Azure not supported" exception has been removed, along with its related
+  mentions. This should unblock the use of the the token-based client constructor.
 
 ## 1.0.0-beta.3 (2024-03-06)