Fix "make check" issues and upgrade npm dependencies

That diff contains three small commits:

• pre-commit-config: Globally exclude tests resources file tree (make check fails otherwise)

• cypress/utils: Fix eslint warning (spotted with make check)

• package.json: Upgrade depencies (notably upgrade jQuery to 3.5 and use recommended dompurify option)

---

Migrated from D3027 (view on Phabricator)