build(deps): bump xunit in /Notation.Plugin.AzureKeyVault.Tests

Bumps [xunit](https://github.com/xunit/xunit) from 2.9.0 to 2.9.2.
- [Commits](xunit/xunit@2.9.0...2.9.2)

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

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

Author: dependabot[bot]

Notation.Plugin.AzureKeyVault.Tests/Notation.Plugin.AzureKeyVault.Tests.csproj

@@ -12,7 +12,7 @@
     <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="Moq.AutoMock" Version="3.5.0" />
     <PackageReference Include="System.Security.Cryptography.Pkcs" Version="8.0.0" />
-    <PackageReference Include="xunit" Version="2.9.0" />
+    <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>