build: support Node.js 18.x

Author: dougwilson

.github/workflows/ci.yml

@@ -30,6 +30,7 @@ jobs:
         - Node.js 15.x
         - Node.js 16.x
         - Node.js 17.x
+        - Node.js 18.x
 
         include:
         - name: Node.js 0.8
@@ -107,6 +108,9 @@ jobs:
         - name: Node.js 17.x
           node-version: "17.9"
 
+        - name: Node.js 18.x
+          node-version: "18.0"
+
     steps:
     - uses: actions/checkout@v2