Bump Swashbuckle.AspNetCore from 5.6.3 to 9.0.0

---
updated-dependencies:
- dependency-name: Swashbuckle.AspNetCore
  dependency-version: 9.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

code/src/AttendeeSite/AttendeeSite.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Swashbuckle.AspNetCore" Version="5.6.3" />
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="9.0.0" />
   </ItemGroup>
 
 </Project>