replace the unsigned dll with signed (Azure#27009)

* replace the unsigned dll with signed

* Update ChangeLog.md

---------

Co-authored-by: Yabo Hu <[email protected]>

Author: Nickcandy

src/Accounts/Accounts/ChangeLog.md

@@ -19,6 +19,9 @@
 -->
 
 ## Upcoming Release
+* Fixed unsigned dll:
+    - `System.Buffers.dll`
+    - `System.Memory.dll`
 
 ## Version 4.0.1
 * Upgraded nuget package to signed package.