chore(deps): update dependency azure.identity to 1.21.0

Author: github-actions[bot]

AzureCliCredentialProxy.csproj

@@ -13,7 +13,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Azure.Identity" Version="1.19.0" />
+    <PackageReference Include="Azure.Identity" Version="1.21.0" />
     <PackageReference Include="Workleap.DotNet.CodingStandards" Version="1.2.4">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>