Bump xunit from 2.6.6 to 2.9.3

---
updated-dependencies:
- dependency-name: xunit
  dependency-version: 2.9.3
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

test/AzureFunctionsOpenApiFluentValidationExtensions.Tests/AzureFunctionsOpenApiFluentValidationExtensions.Tests.csproj

@@ -8,7 +8,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
     <PackageReference Include="Moq" Version="4.18.4" />
-    <PackageReference Include="xunit" Version="2.6.6" />
+    <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.6">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>