Updating changelog for azblob 1.2.1 release (#22140)

Author: souravgupta-msft

sdk/storage/azblob/CHANGELOG.md

@@ -1,13 +1,11 @@
 # Release History
 
-## 1.2.1 (Unreleased)
+## 1.2.1 (2023-12-13)
 
 ### Features Added
 
 * Exposed GetSASURL from specialized clients
 
-### Breaking Changes
-
 ### Bugs Fixed
 
 * Fixed case in Blob Batch API when blob path has / in it. Fixes [#21649](https://github.com/Azure/azure-sdk-for-go/issues/21649).