chore: update customizations to support ktor v3 (#72)

Author: anssari1

customizations/core/src/main/kotlin/com/expediagroup/sdk/core/plugin/serialization/ContentNegotiation.kt

@@ -69,6 +69,7 @@ class {{clientClassname}}Client private constructor(clientConfiguration: XapClie
             appendHeaders(extraHeaders)
             contentType(ContentType.Application.Json)
             setBody(operation.requestBody)
+            exclude(ContentType.Application.Json)
         }
     }