prepare release for resorucemanager (Azure#39784)

Author: ArcturusZhang

sdk/resourcemanager/Azure.ResourceManager/CHANGELOG.md

@@ -1,15 +1,11 @@
 # Release History
 
-## 1.9.0-beta.1 (Unreleased)
-
-### Features Added
-
-### Breaking Changes
-
-### Bugs Fixed
+## 1.8.1 (2023-11-07)
 
 ### Other Changes
 
+- Refines the `JsonConverter` of `ManagedServiceIdentityType` to include only its string literal value.
+
 ## 1.8.0 (2023-11-02)
 
 ### Features Added

sdk/resourcemanager/Azure.ResourceManager/src/Azure.ResourceManager.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <Version>1.9.0-beta.1</Version>
+    <Version>1.8.1</Version>
     <!--The ApiCompatVersion is managed automatically and should not generally be modified manually.-->
     <ApiCompatVersion>1.8.0</ApiCompatVersion>
     <PackageId>Azure.ResourceManager</PackageId>