chore: bump Microsoft.Extensions.Diagnostics.Testing in /src (#458)

Bumps [Microsoft.Extensions.Diagnostics.Testing](https://github.com/dotnet/extensions) from 9.0.0 to 9.1.0.
- [Release notes](https://github.com/dotnet/extensions/releases)
- [Commits](https://github.com/dotnet/extensions/commits)

---
updated-dependencies:
- dependency-name: Microsoft.Extensions.Diagnostics.Testing
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

src/Directory.Packages.props

@@ -5,7 +5,7 @@
   <ItemGroup>
     <PackageVersion Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.22.0" />
     <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.1" />
-    <PackageVersion Include="Microsoft.Extensions.Diagnostics.Testing" Version="9.0.0" />
+    <PackageVersion Include="Microsoft.Extensions.Diagnostics.Testing" Version="9.1.0" />
     <PackageVersion Include="Microsoft.Extensions.Options" Version="9.0.1" />
     <PackageVersion Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="9.0.1" />
     <PackageVersion Include="Microsoft.Extensions.Options.DataAnnotations" Version="9.0.0" />