Update dependency Microsoft.NET.Test.Sdk to v18 (#80)

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

Author: renovate[bot]

test/Soenneker.Git.LibGit2Sharp.Tests/Soenneker.Git.LibGit2Sharp.Tests.csproj

@@ -19,7 +19,7 @@
     </ItemGroup>
 
     <ItemGroup>
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
         <PackageReference Include="coverlet.collector" Version="6.0.4">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
             <PrivateAssets>all</PrivateAssets>