Passing `contentType` by reference instead of by Value for Go StreamContent

The func `requestInfo.SetStreamContentAndContentType`  in Go expects the content type string to be passed by value and not by reference https://github.com/microsoft/kiota-abstractions-go/blob/920cc73050b562c875f3c7a88ba93197e52dbe68/request_information.go#L232C36-L232C58

The var `contentType` should be cast to pass by val