deps: Bump Microsoft.AspNetCore.OpenApi from 8.0.0 to 8.0.21 (#466)

---
updated-dependencies:
- dependency-name: Microsoft.AspNetCore.OpenApi
  dependency-version: 8.0.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

src/AiDotNet.Serving/AiDotNet.Serving.csproj

@@ -10,7 +10,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.21" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
   </ItemGroup>