Bump core-js from 3.19.1 to 3.20.2

Bumps [core-js](https://github.com/zloirock/core-js) from 3.19.1 to 3.20.2.
- [Release notes](https://github.com/zloirock/core-js/releases)
- [Changelog](https://github.com/zloirock/core-js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/zloirock/core-js/compare/v3.19.1...v3.20.2)

---
updated-dependencies:
- dependency-name: core-js
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -67,7 +67,7 @@
     "blurhash": "^1.1.4",
     "classlist.js": "https://github.com/eligrey/classList.js/archive/1.2.20180112.tar.gz",
     "classnames": "^2.3.1",
-    "core-js": "^3.19.1",
+    "core-js": "^3.20.2",
     "date-fns": "^2.28.0",
     "dompurify": "^2.3.4",
     "epubjs": "^0.3.90",
@@ -86,7 +86,7 @@
     "material-design-icons-iconfont": "^6.1.1",
     "native-promise-only": "^0.8.0-a",
     "page": "^1.11.6",
-    "pdfjs-dist": "2.6.347",
+    "pdfjs-dist": "2.12.313",
     "react": "^17.0.2",
     "react-dom": "^17.0.2",
     "resize-observer-polyfill": "^1.5.1",