message: refactor(docs-infra): replace deprecated toPromise usages
  This commit replaces deprecated `Observable.toPromise` usages
  with `lastValueFrom`.
  PR Close
diff: import { ComponentFixture, TestBed } from '@angular/core/testing';
  import { Meta, Title } from '@angular/platform-browser';
  -import { Observable, asapScheduler, of } from 'rxjs';
  +import { Observable, asapScheduler, of, lastValueFrom } from 'rxjs';
  import { EMPTY_HTML, htmlEscape } from 'safevalues';
  import { htmlFromStringKnownToSatisfyTypeContract } from 'safevalues/unsafe/reviewed';
  @@ -302,7 +302,7 @@ describe('DocViewerComponent', () => {
  let loadElementsSpy: jasmine.Spy;
  const doRender = (contents: TrustedHTML | null, id = 'foo') =>
  - docViewer.render({contents, id}).toPromise();
  + lastValueFrom(docViewer.render({contents, id}));
  beforeEach(() => {
  const elementsLoader = TestBed.inject(ElementsLoader) as Partial<ElementsLoader> as MockElementsLoader;
  @@ -578,7 +578,7 @@ describe('DocViewerComponent', () => {
  let oldCurrViewContainer: HTMLElement;
  let oldNextViewContainer: HTMLElement;
  - const doSwapViews = (cb?: () => void) => docViewer.swapViews(cb).toPromise();
  + const doSwapViews = (cb?: () => void) => lastValueFrom(docViewer.swapViews(cb));
  beforeEach(() => {
  oldCurrViewContainer = docViewer.currViewContainer;
  