Updating AzSdk.RP.Props API Tag, .csproj to reflect new Public Preview APIVersion (Azure#19773)

Co-authored-by: Aditi Malladi <amalladi@microsoft.com>

Author: aditimalladi

sdk/extendedlocation/Microsoft.Azure.Management.ExtendedLocation/AzSdk.RP.props

@@ -1,7 +1,7 @@
 <Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <!--This file and it's contents are updated at build time moving or editing might result in build failure. Take due deligence while editing this file-->
   <PropertyGroup>
-    <AzureApiTag>ExtendedLocation_2020-07-15-privatepreview;</AzureApiTag>
+    <AzureApiTag>ExtendedLocation_2021-03-15-preview;</AzureApiTag>
     <PackageTags>$(PackageTags);$(CommonTags);$(AzureApiTag);</PackageTags>
   </PropertyGroup>
 </Project>

sdk/extendedlocation/Microsoft.Azure.Management.ExtendedLocation/src/Microsoft.Azure.Management.ExtendedLocation.csproj

@@ -10,7 +10,7 @@
     <AssemblyTitle>Microsoft Azure Management ExtendedLocation Library</AssemblyTitle>
     <AssemblyName>Microsoft.Azure.Management.ExtendedLocationn</AssemblyName>
     <PackageTags>ExtendedLocation;</PackageTags>
-    <PackageReleaseNotes>Release official public api version 2020-07-15-privatepreview</PackageReleaseNotes>
+    <PackageReleaseNotes>Release official public api version 2021-03-15-preview</PackageReleaseNotes>
   </PropertyGroup>
 
   <PropertyGroup>