php74: Fix a couple of remaining curly-bracket uses

These escaped #65 and just noticed them today when executing
the bundled pear/PHP/scripts/phpcs binary (not reproducible
from web or tests).

Also fix an unrelated typo in CHANGES.md

CHANGES.md

@@ -1,7 +1,7 @@
 Changes in version 2.9.5 (20200401) - Poisson d'avril
 -----------------------------------------------------
 - CONTRIB-8024: Process all files as UTF-8 encoded (defined @ standard level).
-- CONTRIB-6175: Only process PHP file (defined @ standard level).
+- CONTRIB-6175: Only process PHP files (defined @ standard level).
 - [PR#69](https://github.com/moodlehq/moodle-local_codechecker/pull/69): Upgrade PHPCompatibility to 9.3.5+ (9fb3244).
 - CONTRIB-8031: Detect wrong uses of $PAGE and $OUTPUT in renderers and blocks (Tim Hunt).
 - MDLSITE-6093: Don't require MOODLE_INTERNAL check for pure 1-artifact (class, interface, trait) files.

pear/PHP/CodeSniffer.php

@@ -2025,12 +2025,12 @@ public static function isCamelCaps(
             $lastCharWasCaps = $classFormat;
 
             for ($i = 1; $i < $length; $i++) {
-                $ascii = ord($string{$i});
+                $ascii = ord($string[$i]);
                 if ($ascii >= 48 && $ascii <= 57) {
                     // The character is a number, so it cant be a capital.
                     $isCaps = false;
                 } else {
-                    if (strtoupper($string{$i}) === $string{$i}) {
+                    if (strtoupper($string[$i]) === $string[$i]) {
                         $isCaps = true;
                     } else {
                         $isCaps = false;