ci: migrate to GitHub Actions

Due to the recent changes to the Travis CI platform (see [1]), we will
now use GitHub Actions to run the tests.

Reference: https://docs.github.com/en/free-pro-team@latest/actions/guides/building-and-testing-nodejs

[1]: https://blog.travis-ci.com/2020-11-02-travis-ci-new-billing

Backported from master: 312bd35

.github/workflows/ci.yml

@@ -0,0 +1,24 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  test-node:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [8.x]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+      - run: npm ci
+      - run: npm test
+        env:
+          CI: true

README.md

@@ -1,7 +1,7 @@
 
 # Engine.IO: the realtime engine
 
-[![Build Status](https://travis-ci.org/socketio/engine.io.svg?branch=master)](http://travis-ci.org/socketio/engine.io)
+[![Build Status](https://github.com/socketio/engine.io/workflows/CI/badge.svg)](https://github.com/socketio/engine.io/actions)
 [![NPM version](https://badge.fury.io/js/engine.io.svg)](http://badge.fury.io/js/engine.io)
 
 `Engine.IO` is the implementation of transport-based

test/server.js

@@ -932,7 +932,7 @@ describe('server', function () {
     it('should trigger transport close before open for ws', function (done) {
       var opts = { transports: ['websocket'] };
       listen(opts, function (port) {
-        var url = 'ws://%s:%d'.s('0.0.0.50', port);
+        var url = 'ws://%s:%d'.s('0.0.0.0', port);
         var socket = new eioc.Socket(url);
         socket.on('open', function () {
           done(new Error('Test invalidation'));