fix php 7.4 compat

Author: dannyvankooten

src/Dashboard.php

@@ -161,7 +161,7 @@ protected function maybe_show_review_notice(): void
         $notice = new Review_Notice(
             'koko-analytics',
             'koko_analytics_settings',
-            static fn (): array => [
+            fn (): array => [
                 /* translators: %s is the plugin name. */
                 'heading'      => sprintf(__('Enjoying %s?', 'koko-analytics'), 'Koko Analytics'),
                 'body'         => __('A quick review on WordPress.org helps more people find the plugin and helps us keep maintaining it for the long term.', 'koko-analytics'),

src/Review_Notice.php

@@ -120,7 +120,7 @@ private function get_state(): array
         return array_merge($defaults, (array) ($option[$this->state_key] ?? []));
     }
 
-    private function update_state(string $key, mixed $value): void
+    private function update_state(string $key, $value): void
     {
         $option              = (array) get_option($this->option_name, []);
         $state               = (array) ($option[$this->state_key] ?? []);