Bump to symfony 4.4 and related dependencies

Just bump all the symfony requirements to 4.4, also bumping
other dependencies.

Importantly, this requires PHP 7.1.3 or later (versus current
PHP 7.0). Implications are:

1) People will need to stop testing things with 7.0
2) Minimum Moodle version supported will be 3.2 (versus current 3.0)

This will fix moodlehq#21 if agreed to be the route.

composer.json

@@ -74,24 +74,23 @@
     }
   ],
   "require": {
-    "php": ">=7.0.8",
+    "php": ">=7.1.3",
     "moodlehq/moodle-local_codechecker": "^2.9.7",
     "moodlehq/moodle-local_ci": "^1.0.5",
     "moodlehq/moodle-local_moodlecheck": "^1.0.2",
     "sebastian/phpcpd": "^3.0",
     "phpmd/phpmd": "^2.2",
-    "symfony/dependency-injection": "^3.4",
-    "symfony/dotenv": "^3.3",
-    "symfony/filesystem": "^3.3",
-    "symfony/finder": "^3.3",
-    "symfony/console": "^3.3",
-    "symfony/yaml": "^3.3",
-    "symfony/process": "^3.3",
+    "symfony/dotenv": "^4.4",
+    "symfony/filesystem": "^4.4",
+    "symfony/finder": "^4.4",
+    "symfony/console": "^4.4",
+    "symfony/yaml": "^4.4",
+    "symfony/process": "^4.4",
     "php-parallel-lint/php-parallel-lint": "^1.2.0",
     "php-parallel-lint/php-console-highlighter": "^0.5",
     "psr/log": "^1.0",
     "nikic/php-parser": "^3.0",
-    "stecman/symfony-console-completion": "^0.7.0",
+    "stecman/symfony-console-completion": "^0.11.0",
     "marcj/topsort": "^1.0",
     "padraic/phar-updater": "^1.0"
   },
@@ -100,7 +99,7 @@
   },
   "config": {
     "platform": {
-      "php": "7.0.8"
+      "php": "7.1.3"
     }
   },
   "autoload": {