chore(deps): update dependency microsoft.net.test.sdk to v18 (#362)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

src/ReactiveMarbles.PropertyChanged.SourceGenerator.Tests/ReactiveMarbles.PropertyChanged.SourceGenerator.Tests.csproj

@@ -9,7 +9,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.11.0" allowedVersions="[3.11.0]" PrivateAssets="all" />
     <PackageReference Include="System.Reactive" Version="6.0.2" />
     <PackageReference Include="FluentAssertions" Version="6.2.0" />

src/ReactiveMarbles.PropertyChanged.Tests/ReactiveMarbles.PropertyChanged.Tests.csproj

@@ -15,7 +15,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
     <PackageReference Include="Xunit.StaFact" Version="1.2.69" />