message: fix(leaving-ibm): update open attribute; fixes
  ### Related Ticket(s)
  ### Description
  This fixes an attribute in the `leaving-ibm` component to allow it to correctly toggle the open/close states.
  ### Changelog
  **Changed**
  make `open` attribute in `leaving-ibm-composite` boolean
diff: @@ -94,7 +94,7 @@ class DDSLeavingIbmComposite extends ModalRenderMixin(LitElement) {
  renderModal() {
  const { open, leavingIbmCopy, leavingIbmButtonLabel, href } = this;
  return html`
  - <dds-leaving-ibm-modal open="${open}">
  + <dds-leaving-ibm-modal ?open="${open}">
  <bx-modal-header>
  <bx-modal-close-button></bx-modal-close-button>
  <dds-leaving-ibm-modal-heading>${leavingIbmCopy?.LEAVING001}</dds-leaving-ibm-modal-heading>
  