Update Simplify.Xml requirement from 1.2.* to 1.3.*

Updates the requirements on [Simplify.Xml](https://github.com/SimplifyNet/Simplify) to permit the latest version.
- [Release notes](https://github.com/SimplifyNet/Simplify/releases)
- [Commits](SimplifyNet/Simplify@Simplify.Xml.1.2...Simplify.Xml.1.3)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

src/Simplify.Web.Tests/Simplify.Web.Tests.csproj

@@ -20,7 +20,7 @@
 		<PackageReference Include="Moq" Version="4.16.*" />
 		<PackageReference Include="NUnit" Version="3.13.*" />
 		<PackageReference Include="NUnit3TestAdapter" Version="3.17.*" />
-		<PackageReference Include="Simplify.Xml" Version="1.2.*" />
+		<PackageReference Include="Simplify.Xml" Version="1.3.*" />
 	</ItemGroup>
 	<ItemGroup>
 		<ProjectReference Include="..\Simplify.Web\Simplify.Web.csproj" />