Fix PHP 7.3 CI checks

Author: SbWereWolf

src/SbWereWolf/XmlNavigator/Extraction/PrettyPrintComposer.php

@@ -257,6 +257,9 @@ private static function collectAttributes(XMLReader $reader): array
         return $attributes;
     }
 
+    /**
+     * @param array<mixed, mixed> $value
+     */
     private static function isList(array $value): bool
     {
         return $value === array_values($value);

src/SbWereWolf/XmlNavigator/Navigation/XmlElement.php

@@ -260,6 +260,9 @@ private static function isHierarchySequence($value): bool
         return true;
     }
 
+    /**
+     * @param array<mixed, mixed> $value
+     */
     private static function isList(array $value): bool
     {
         return $value === array_values($value);