Bump xunit and xunit.runner.visualstudio

Bumps xunit from 2.9.2 to 2.9.3
Bumps xunit.runner.visualstudio from 2.8.2 to 3.1.5

---
updated-dependencies:
- dependency-name: xunit
  dependency-version: 2.9.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: xunit
- dependency-name: xunit
  dependency-version: 2.9.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: xunit
- dependency-name: xunit.runner.visualstudio
  dependency-version: 3.1.5
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: xunit
- dependency-name: xunit.runner.visualstudio
  dependency-version: 3.1.5
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: xunit
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

tests/Microsoft.Graph.DotnetCore.Test/Microsoft.Graph.DotnetCore.Test.csproj

@@ -18,8 +18,8 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="Moq" Version="4.20.72" />
-    <PackageReference Include="xunit" Version="2.9.2" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>