chore(deps): update dependency microsoft.aspnetcore.openapi to 8.0.21

Author: renovate[bot]

Samples/WeatherApi/WeatherApi.csproj

@@ -9,7 +9,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.20" />
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.21" />
     <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.22.1" />
     <PackageReference Include="OpenTelemetry.Instrumentation.Runtime" Version="1.12.0" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="7.3.2" />