[Batch] Beta Data Plane SDK 15.1.0b1 (replacing 15.0.0b3) (#43590)

* Update to version 15.1.0b1 instead of 15.0.0b3 due to CLI conflict

* Update release date to current month

---------

Co-authored-by: Rena Chen <rechen@microsoft.com>

Author: cRui861

sdk/batch/azure-batch/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## 15.0.0b3 (2025-09-01)
+## 15.1.0b1 (2025-10-01)
 
 ### Features Added
 

sdk/batch/azure-batch/azure/batch/_version.py

@@ -6,4 +6,4 @@
 # Changes may cause incorrect behavior and will be lost if the code is regenerated.
 # --------------------------------------------------------------------------
 
-VERSION = "15.0.0b3"
+VERSION = "15.1.0b1"