Add node v20 to the PR build matrix (#204)

Author: jasongin

.github/workflows/build.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ windows-latest, macos-latest, ubuntu-latest ]
-        node-version: [ 18.x ]
+        node-version: [ 18.x, 20.x ]
         configuration: [ Release ]
       fail-fast: false  # Don't cancel other jobs when one job fails