Update to node 20.x to unblock some styling work

.github/workflows/nodejs.yml

@@ -29,7 +29,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [16.x, 18.x, 20.x]
+        node-version: [20.x]
 
     steps:
       - uses: actions/checkout@v3
@@ -50,7 +50,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [18.x, 20.x]
+        node-version: [20.x]
 
     steps:
       - uses: actions/checkout@v3
@@ -72,7 +72,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [16.x]
+        node-version: [20.x]
 
     steps:
       - uses: actions/checkout@v3

custom-jest-environment.js

@@ -17,6 +17,8 @@
 // Inspired by https://github.com/facebook/jest/issues/7780#issuecomment-615890410
 // This file is used in `npm test` to override a few globals on top of jsdom.
 
+const { ReadableStream } = require('web-streams-polyfill/dist/polyfill.js');
+
 const JsdomEnvironment = require('jest-environment-jsdom');
 const dns = require('dns');
 
@@ -38,6 +40,7 @@ class EmulatorUiTestEnvironment extends JsdomEnvironment {
           clearImmediate: clearImmediate,
           setInterval: setInterval,
           setTimeout: setTimeout,
+          ReadableStream: ReadableStream,
         }),
       })
     );