Update minimum PHP version throughout the code

docs/simplesamlphp-upgrade-notes-1.19.md

 Upgrade notes for SimpleSAMLphp 1.19
 ====================================
 
-The minimum PHP version required is now PHP 7.0.
+The minimum PHP version required is now PHP 7.1.
 
 SAML 1 / Shib 1.3 support is now deprecated and will start logging notices
 when used. It will be removed in SimpleSAMLphp 2.0.

modules/admin/lib/Controller/Config.php

@@ -157,11 +157,11 @@ class Config
                 'descr' => [
                     Translate::noop('PHP %minimum% or newer is needed. You are running: %current%'),
                     [
-                        '%minimum%' => '7.0',
+                        '%minimum%' => '7.1',
                         '%current%' => explode('-', phpversion())[0]
                     ]
                 ],
-                'enabled' => version_compare(phpversion(), '7.0', '>=')
+                'enabled' => version_compare(phpversion(), '7.1', '>=')
             ]
         ];
         $store = $this->config->getString('store.type', '');

modules/core/hooks/hook_sanitycheck.php

@@ -28,7 +28,7 @@ function core_hook_sanitycheck(&$hookinfo)
         $hookinfo['info'][] = '[core] In config.php technicalcontact_email is set properly';
     }
 
-    if (version_compare(phpversion(), '7.0', '>=')) {
+    if (version_compare(phpversion(), '7.1', '>=')) {
         $hookinfo['info'][] = '[core] You are running a PHP version suitable for SimpleSAMLphp.';
     } else {
         $hookinfo['errors'][] = '[core] You are running an old PHP installation. ' .

modules/core/www/frontpage_config.php

@@ -123,8 +123,8 @@ if (\SimpleSAML\Module::isModuleEnabled('radius')) {
 $funcmatrix = [];
 $funcmatrix[] = [
     'required' => 'required',
-    'descr' => 'PHP Version >= 7.0. You run: ' . phpversion(),
-    'enabled' => version_compare(phpversion(), '7.0', '>=')
+    'descr' => 'PHP Version >= 7.1. You run: ' . phpversion(),
+    'enabled' => version_compare(phpversion(), '7.1', '>=')
 ];
 foreach ($functionchecks as $func => $descr) {
     $funcmatrix[] = ['descr' => $descr[1], 'required' => $descr[0], 'enabled' => function_exists($func)];