Drop support for PHP 5

.travis.yml

@@ -49,8 +49,6 @@ jobs:
         - CHECKS=phpcs
 
     # Test remaining supported PHP versions
-    - stage: Test
-      php: "5.6"
     - stage: Test
       php: "7.0"
     - stage: Test
@@ -62,7 +60,7 @@ jobs:
 
     # Test against lowest supported dependencies
     - stage: Test
-      php: "5.6"
+      php: "7.0"
       env:
         - COMPOSER_OPTIONS=--prefer-lowest
 

composer.json

@@ -10,14 +10,14 @@
         { "name": "Katherine Walker", "email": "katherine.walker@mongodb.com" }
     ],
     "require": {
-        "php": "^5.6 || ^7.0",
+        "php": "^7.0",
         "ext-hash": "*",
         "ext-json": "*",
         "ext-mongodb": "^1.7"
     },
     "require-dev": {
-        "phpunit/phpunit": "^5.7.27 || ^6.4 || ^8.3",
-        "sebastian/comparator": "^1.0 || ^2.0 || ^3.0",
+        "phpunit/phpunit": "^6.4 || ^8.3",
+        "sebastian/comparator": "^2.0 || ^3.0",
         "squizlabs/php_codesniffer": "^3.4",
         "symfony/phpunit-bridge": "^4.4@dev"
     },