Migrate from Travis CI to GitHub actions

Since Travis CI is no longer free for OS projects and GH Actions is a good replacement
Also restrict PHP version to 7.3+ as the current setup won't work with older versions anyway.

.github/workflows/tests.yml

@@ -0,0 +1,42 @@
+name: tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  tests:
+    strategy:
+      matrix:
+        php-versions: ['7.3', '7.4']
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+
+      - name: Cache Composer packages
+        id: composer-cache
+        uses: actions/cache@v2
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-
+
+      - name: Install dependencies
+        uses: php-actions/composer@v6
+        with:
+          version: 2
+          php_version: ${{ matrix.php-versions }}
+
+      - name: Run test suite
+        run: vendor/bin/phpunit

README.md

@@ -1,7 +1,7 @@
 phpnsc
 ======
 
-[![Build Status](https://travis-ci.com/researchgate/phpnsc.svg?branch=master)](https://travis-ci.com/researchgate/phpnsc)
+![Test status](https://github.com/researchgate/phpnsc/actions/workflows/tests.yml/badge.svg)
 [![Latest Stable Version](https://poser.pugx.org/rg/phpnsc/v/stable)](https://packagist.org/packages/rg/phpnsc)
 [![Total Downloads](https://poser.pugx.org/rg/phpnsc/downloads)](https://packagist.org/packages/rg/phpnsc)
 [![License](https://poser.pugx.org/rg/phpnsc/license)](https://packagist.org/packages/rg/phpnsc)

composer.json

@@ -9,7 +9,7 @@
         }
     ],
     "require": {
-        "php": "^7.1",
+        "php": "^7.3",
         "symfony/console" : "^2.1|^3.0|^4.0|^5.0",
         "phpunit/php-timer": "^4.0|^5.0"
     },