Install psalm as dev, sync scripts updates

vendor/felixfbecker/language-server-protocol/src/DidChangeWatchedFilesClientCapabilities.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace LanguageServerProtocol;
+
+class DidChangeWatchedFilesClientCapabilities
+{
+    /**
+     * Did change watched files notification supports dynamic registration.
+     * Please note that the current protocol doesn't support static
+     * configuration for file changes from the server side.
+     *
+     * @var bool|null
+     */
+    public $dynamicRegistration;
+
+    public function __construct(
+        bool $dynamicRegistration = null
+    ) {
+        $this->dynamicRegistration = $dynamicRegistration;
+    }
+}