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 +1,26 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '0 0 * * 0'
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+      fail-fast: false
+    steps:
+    - name: Checkout
+      uses: actions/[email protected]
+
+    - name: Build project
+      uses: nicledomaS/[email protected]
+      with:
+        submodule_update: ON
+        run_tests: ON
+        unit_test_build: -DBUILD_UNIT_TESTS=ON
+        cmake_args: -DCMAKE_CXX_FLAGS=-std=c++11

.travis.yml

@@ -1,5 +1,6 @@
 # Socket.IO C++ Client
-[![Build Status](https://travis-ci.org/socketio/socket.io-client-cpp.svg)](https://travis-ci.org/socketio/socket.io-client-cpp)
+
+[![Build Status](https://github.com/socketio/socket.io-client-cpp/workflows/CI/badge.svg)](https://github.com/socketio/socket.io-client-cpp/actions)
 
 By virtue of being written in C++, this client works in several different platforms. The [examples](https://github.com/socketio/socket.io-client-cpp/tree/master/examples) folder contains an iPhone, QT and Console example chat client! It depends on [websocket++](https://github.com/zaphoyd/websocketpp) and is inspired by [socket.io-clientpp](https://github.com/ebshimizu/socket.io-clientpp).