Add JSDom 21.0.0 to the CI

Author: gzm0

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
       fail-fast: false
       matrix:
         scalaversion: ["2.11.12", "2.12.10", "2.13.1"]
-        jsdomversion: ["10.0.0", "16.0.0"]
+        jsdomversion: ["10.0.0", "16.0.0", "21.0.0"]
     steps:
       - uses: actions/checkout@v2
       - uses: olafurpg/setup-scala@v10