Fix NU1011: Replace floating package version with fixed version in Central Package Management (#3099)

Author: rajkumar-rangaraj

Directory.Packages.props

@@ -107,8 +107,7 @@
   -->
 
   <ItemGroup Label="AspNetCore Testing">
-    <!-- Note: Version ranges will be overridden per-framework in project files using Update -->
-    <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="[8.*-*,9.0)" />
+    <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.11" />
   </ItemGroup>
 
   <!--