eng: update test package dependencies to current stable versions

- Microsoft.NET.Test.Sdk 17.10.0 → 18.3.0
- xunit 2.8.0 → 2.9.3
- xunit.runner.visualstudio 2.8.0 → 2.8.2

All 4530 tests pass.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: github-actions[bot]

src/FSharp.Control.TaskSeq.Test/FSharp.Control.TaskSeq.Test.fsproj

@@ -80,9 +80,9 @@
     -->
     <PackageReference Update="FSharp.Core" Version="6.0.1" />
     <PackageReference Include="FsUnit.xUnit" Version="6.0.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
-    <PackageReference Include="xunit" Version="2.8.0" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.0">
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>