Fix deprecation warnings on PHP 7.4.

src/Console/ConsoleOptionParser.php

@@ -1073,8 +1073,8 @@ class ConsoleOptionParser
         if (substr($name, 0, 2) === '--') {
             return isset($this->_options[substr($name, 2)]);
         }
-        if ($name{0} === '-' && $name{1} !== '-') {
-            return isset($this->_shortOptions[$name{1}]);
+        if ($name[0] === '-' && $name[1] !== '-') {
+            return isset($this->_shortOptions[$name[1]]);
         }
 
         return false;

src/Filesystem/Folder.php

@@ -596,7 +596,7 @@ class Folder
         foreach ($iterator as $itemPath => $fsIterator) {
             if ($skipHidden) {
                 $subPathName = $fsIterator->getSubPathname();
-                if ($subPathName{0} === '.' || strpos($subPathName, DIRECTORY_SEPARATOR . '.') !== false) {
+                if ($subPathName[0] === '.' || strpos($subPathName, DIRECTORY_SEPARATOR . '.') !== false) {
                     continue;
                 }
             }

src/TestSuite/TestCase.php

@@ -492,7 +492,7 @@ abstract class TestCase extends BaseTestCase
                 $tags = (string)$tags;
             }
             $i++;
-            if (is_string($tags) && $tags{0} === '<') {
+            if (is_string($tags) && $tags[0] === '<') {
                 $tags = [substr($tags, 1) => []];
             } elseif (is_string($tags)) {
                 $tagsTrimmed = preg_replace('/\s+/m', '', $tags);

src/View/Helper/FormHelper.php

@@ -2061,7 +2061,7 @@ class FormHelper extends Helper
         if ($isUrl) {
             $options['src'] = $caption;
         } elseif ($isImage) {
-            if ($caption{0} !== '/') {
+            if ($caption[0] !== '/') {
                 $url = $this->Url->webroot(Configure::read('App.imageBaseUrl') . $caption);
             } else {
                 $url = $this->Url->webroot(trim($caption, '/'));