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

Author: darrachequesne

.github/workflows/ci.yml

@@ -0,0 +1,37 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '0 0 * * 0'
+
+jobs:
+  test-node:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [10.x, 12.x, 14.x]
+
+    services:
+      redis:
+        image: redis
+        options: >-
+          --health-cmd "redis-cli ping"
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+        ports:
+          - 6379:6379
+
+    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

.travis.yml

@@ -1,6 +1,6 @@
 # socket.io-redis
 
-[![Build Status](https://travis-ci.org/socketio/socket.io-redis.svg?branch=master)](https://travis-ci.org/socketio/socket.io-redis)
+[![Build Status](https://github.com/socketio/socket.io-redis/workflows/CI/badge.svg?branch=master)](https://github.com/socketio/socket.io-redis/actions)
 [![NPM version](https://badge.fury.io/js/socket.io-redis.svg)](http://badge.fury.io/js/socket.io-redis)
 
 ## Table of contents