Bump System.IO.Abstractions.TestingHelpers from 19.1.18 to 19.2.1 (#1221)

Bumps [System.IO.Abstractions.TestingHelpers](https://github.com/TestableIO/System.IO.Abstractions) from 19.1.18 to 19.2.1.
- [Release notes](https://github.com/TestableIO/System.IO.Abstractions/releases)
- [Commits](https://github.com/TestableIO/System.IO.Abstractions/compare/v19.1.18...v19.2.1)

---
updated-dependencies:
- dependency-name: System.IO.Abstractions.TestingHelpers
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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tests/KubernetesClient.Tests/KubernetesClient.Tests.csproj

@@ -9,7 +9,7 @@
       <PackageReference Include="MartinCostello.Logging.XUnit" Version="0.3.0" />
       <PackageReference Include="FluentAssertions" Version="6.10.0" />
       <PackageReference Include="Microsoft.Extensions.Logging" Version="7.0.0" />
-      <PackageReference Include="System.IO.Abstractions.TestingHelpers" Version="19.1.18" />
+      <PackageReference Include="System.IO.Abstractions.TestingHelpers" Version="19.2.1" />
       <PackageReference Include="System.Reactive" Version="5.0.0" />
       <PackageReference Include="Nito.AsyncEx" Version="5.1.2" />
       <PackageReference Include="Portable.BouncyCastle" Version="1.9.0" />