MDL-67031 s3: php74 fixup for class S3 v0.5.1

repository/s3/README_MOODLE.txt

@@ -6,3 +6,9 @@ Cloned from git://github.com/tpyo/amazon-s3-php-class.git
 
 https://github.com/tpyo/amazon-s3-php-class
 http://undesigned.org.za/2007/10/22/amazon-s3-php-class
+
+Local changes applied:
+(verify on each upgrade of the library if they have been applied
+upstream. Remove the local changes if so)
+
+MDL-67031 php74 compliance. Change curly to square braces.

repository/s3/S3.php

@@ -2354,7 +2354,7 @@ final class S3Request
 			elseif ($header == 'Content-Type')
 				$this->response->headers['type'] = $value;
 			elseif ($header == 'ETag')
-				$this->response->headers['hash'] = $value{0} == '"' ? substr($value, 1, -1) : $value;
+				$this->response->headers['hash'] = $value[0] == '"' ? substr($value, 1, -1) : $value;
 			elseif (preg_match('/^x-amz-meta-.*$/', $header))
 				$this->response->headers[$header] = $value;
 		}