Change swagger dictionary type mapping

Jellyfin.Server/Extensions/ApiServiceCollectionExtensions.cs

@@ -216,6 +216,9 @@ namespace Jellyfin.Server.Extensions
                         })
                 });
 
+            /*
+             * Support BlurHash dictionary
+             */
             options.MapType<Dictionary<ImageType, Dictionary<string, string>>>(() =>
                 new OpenApiSchema
                 {
@@ -223,9 +226,18 @@ namespace Jellyfin.Server.Extensions
                     Properties = typeof(ImageType).GetEnumNames().ToDictionary(
                         name => name,
                         name => new OpenApiSchema
+                        {
+                            Type = "object", Properties = new Dictionary<string, OpenApiSchema>
+                            {
+                                {
+                                    "string",
+                                    new OpenApiSchema
                                     {
                                         Type = "string",
                                         Format = "string"
+                                    }
+                                }
+                            }
                         })
                 });
         }