chore: run CI tests on Node 20 (#629)

Author: benmccann

.github/workflows/ci.yml

@@ -81,6 +81,8 @@ jobs:
             os: ubuntu-latest
           - node: 18
             os: ubuntu-latest
+          - node: 20
+            os: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3