feat: update dependencies, add linting, fix codebase, cleanup (#11)

* chore(deps): update dependencies

* feat(tests): add matrix testing, problem matcher

* feat(lint): add php-cs-fixer, fix codebase

.php-cs-fixer.dist.php

@@ -0,0 +1,15 @@
+<?php
+
+$finder = (new PhpCsFixer\Finder())
+    ->in(__DIR__);
+
+return (new PhpCsFixer\Config())
+    ->setRules([
+        '@PhpCsFixer' => true,
+        '@PHP74Migration' => true,
+        '@PSR12' => true,
+        'strict_param' => true,
+        'array_syntax' => ['syntax' => 'short'],
+    ])
+    ->setFinder($finder)
+;