deps: Bump Microsoft.OpenApi from 1.6.28 to 2.3.9

---
updated-dependencies:
- dependency-name: Microsoft.OpenApi
  dependency-version: 2.3.9
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

Directory.Packages.props

@@ -20,7 +20,7 @@
     <PackageVersion Include="SwashBuckle.AspNetCore" Version="9.0.6" />
     <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="9.0.10" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
-    <PackageVersion Include="Microsoft.OpenApi" Version="1.6.28" />
+    <PackageVersion Include="Microsoft.OpenApi" Version="2.3.9" />
     <PackageVersion Include="xunit.v3" Version="3.1.0" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.5" />
   </ItemGroup>