Release v26.4.0

Added

• The bundled PDF.js (pdf.mjs and pdf.worker.mjs) now ships with core-js
  polyfills for five newer JavaScript APIs the PDF.js 6 build relies on —
  Map.prototype.getOrInsertComputed, Promise.try, Promise.withResolvers,
  Uint8Array.prototype.toHex, and URL.parse. Without them the viewer threw on
  startup in browsers that predate those APIs; it now runs on those older engines.
  The polyfills are injected into the two bundles at build time with esbuild, so
  consumers pull in nothing new at runtime — core-js stays a build-only
  dependency. Thanks to @delagen for the contribution. (#379)