Update Composer, update everything

web/core/profiles/testing_requirements/testing_requirements.info.yml

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+name: 'Testing requirements'
+type: profile
+description: 'Profile for testing hook_requirements().'
+version: VERSION
+core: 8.x
+hidden: true

web/core/profiles/testing_requirements/testing_requirements.install

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+<?php
+
+/**
+ * @file
+ * Install hooks for test profile.
+ */
+
+/**
+ * Implements hook_requirements().
+ */
+function testing_requirements_requirements($phase) {
+  $requirements = [];
+
+  if ($phase === 'install') {
+    $requirements['testing_requirements'] = [
+      'title' => t('Testing requirements'),
+      'severity' => REQUIREMENT_ERROR,
+      'description' => t('Testing requirements failed requirements.'),
+    ];
+  }
+
+  return $requirements;
+}