Bump Microsoft.OpenApi from 1.6.5 to 1.6.6 in /src

Bumps [Microsoft.OpenApi](https://github.com/Microsoft/OpenAPI.NET) from 1.6.5 to 1.6.6.
- [Release notes](https://github.com/Microsoft/OpenAPI.NET/releases)
- [Commits](microsoft/OpenAPI.NET@1.6.5...1.6.6)

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

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

src/IoTHub.Portal.Server/IoTHub.Portal.Server.csproj

@@ -62,7 +62,7 @@
     </PackageReference>
     <PackageReference Include="Microsoft.Extensions.Http.Polly" Version="7.0.9" />
     <PackageReference Include="Microsoft.Graph" Version="5.19.0" />
-    <PackageReference Include="Microsoft.OpenApi" Version="1.6.5" />
+    <PackageReference Include="Microsoft.OpenApi" Version="1.6.6" />
     <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.18.1" />
     <PackageReference Include="Microsoft.Identity.Web" Version="2.13.0" />
     <PackageReference Include="Microsoft.Identity.Web.UI" Version="2.13.0" />