ci: test against Node v20 and v21 (#182)

Author: G-Rath

.github/workflows/nodejs.yml

@@ -71,7 +71,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [14.x, 16.x, 18.x, 19.x]
+        node-version: [14.x, 16.x, 18.x, 19.x, 20.x, 21.x]
         eslint-version: [7, 8]
     runs-on: ubuntu-latest