Update dependency qunit to v2.21.0 (#606)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

package.json

@@ -66,7 +66,7 @@
     "loader.js": "4.7.0",
     "npm-run-all": "4.1.5",
     "prettier": "2.8.8",
-    "qunit": "2.20.1",
+    "qunit": "2.21.0",
     "qunit-dom": "3.1.2",
     "release-it": "16.3.0",
     "release-it-lerna-changelog": "5.0.0",