Bump Xamarin.Essentials from 1.8.0 to 1.8.1 in /Source

Bumps [Xamarin.Essentials](https://github.com/xamarin/Essentials) from 1.8.0 to 1.8.1.
- [Release notes](https://github.com/xamarin/Essentials/releases)
- [Commits](xamarin/Essentials@1.8.0...1.8.1)

---
updated-dependencies:
- dependency-name: Xamarin.Essentials
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Source/DotNetGraphQL.Mobile/DotNetGraphQL.Mobile.csproj

@@ -6,7 +6,7 @@
     </PropertyGroup>
     <ItemGroup>
         <PackageReference Include="Xamarin.Forms" Version="5.0.0.2622" />
-        <PackageReference Include="Xamarin.Essentials" Version="1.8.0" />
+        <PackageReference Include="Xamarin.Essentials" Version="1.8.1" />
         <PackageReference Include="AsyncAwaitBestPractices.MVVM" Version="6.0.6" />
         <PackageReference Include="Xam.Plugins.Forms.ImageCircle" Version="3.1.1.1-beta" />
         <PackageReference Include="modernhttpclient-updated" Version="3.4.3" />