continuous-integration.yml: Add Node.js 20 to the testing (#5450)

Author: cclauss

.github/workflows/continuous-integration.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         operating-system: [ubuntu-latest, macos-latest, windows-latest]
-        node-version: [12.x, 14.x, 16.x, 17.x, 18.x]
+        node-version: [12.x, 14.x, 16.x, 18.x, 20.x]
 
     steps:
     - uses: actions/checkout@v3