Fix BC break when using RFC3339 constants with Zulu timezone

Author: alganet

library/Helpers/CanValidateDateTime.php

@@ -16,6 +16,8 @@
 use function date_default_timezone_get;
 use function date_parse_from_format;
 use function preg_match;
+use function str_contains;
+use function str_replace;
 
 /**
  * Helper to handle date/time.
@@ -49,6 +51,10 @@ private function isDateTime(string $format, string $value): bool
                 new DateTimeZone(date_default_timezone_get())
             );
 
+            if ($format === DateTime::RFC3339_EXTENDED && str_contains($value, 'Z')) {
+                $value = str_replace('Z', '+00:00', $value);
+            }
+
             if ($formattedDate === false || $value !== $formattedDate->format($format)) {
                 return false;
             }

tests/unit/Helpers/CanValidateDateTimeTest.php

@@ -9,6 +9,7 @@
 
 namespace Respect\Validation\Helpers;
 
+use DateTime;
 use Respect\Validation\Test\TestCase;
 
 /**
@@ -57,6 +58,7 @@ public static function providerForValidDateTime(): array
             ['Y-m-d\TH:i:sP', '2018-01-30T19:04:35+00:00'],
             ['r', 'Tue, 30 Jan 2018 19:06:01 +0000'],
             ['D, d M Y H:i:s O', 'Tue, 30 Jan 2018 19:06:01 +0000'],
+            [DateTime::RFC3339_EXTENDED, '2014-04-12T23:20:50.052Z'],
         ];
     }