Update tested node versions

See ConsenSys-archive#12 (comment)

Author: wbt

.github/workflows/nodejs.yml

@@ -24,7 +24,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [12.x, 14.x]
+        node-version: [14.x, 16.x, 18.x]
 
     name: Node v${{ matrix.node-version }}
     steps: