chore(deps): update dependency microsoft.openapi to 1.6.28

Author: renovate[bot]

Directory.Packages.props

@@ -36,7 +36,7 @@
     <PackageVersion Include="Microsoft.Extensions.Diagnostics.HealthChecks" Version="9.0.7" />
     <PackageVersion Include="Microsoft.Extensions.Http" Version="9.0.7" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="9.0.7" />
-    <PackageVersion Include="Microsoft.OpenApi" Version="1.6.24" />
+    <PackageVersion Include="Microsoft.OpenApi" Version="1.6.28" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageVersion Include="NodaTime.Serialization.JsonNet" Version="3.2.0" />
     <PackageVersion Include="Npgsql" Version="9.0.3" />