Update deps project to .NET 9 (Azure#49575)

Author: weshaggard

eng/scripts/dependencies/azure-sdk.deps.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <OutputType>Exe</OutputType>
     <EnableDefaultItems>false</EnableDefaultItems>
     <!--
@@ -19,4 +19,4 @@
   </Target>
 
   <Target Name="GenerateDepsFile" DependsOnTargets="ListProjects;Restore;GeneratePublishDependencyFile" />
-</Project>
+</Project>