ci: add Node.js 20 in the test matrix

Reference: https://github.com/nodejs/Release

Author: darrachequesne

.github/workflows/ci.yml

@@ -12,7 +12,9 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [16]
+        node-version:
+          - 16
+          - 20
 
     steps:
       - name: Checkout repository

test/index.js

@@ -22,6 +22,7 @@ if (typeof ArrayBuffer !== "undefined") {
   require("./binary-fallback");
 }
 
-if (Blob) {
+// Blob is available in Node.js since v18, but not yet supported by the `engine.io-parser` package
+if (Blob && env.browser) {
   require("./blob");
 }