chore: fix phpstan errors

src/BusProNet/Traits/SortByPriceTrait.php

@@ -28,9 +28,9 @@ trait SortByPriceTrait
      * collections in the application. Items are sorted from lowest to highest price,
      * with null prices being treated as zero (appearing first).
      *
-     * @param array $items Array of objects with a price property to sort
+     * @param array<array-key, object> $items Array of objects with a price property to sort
      *
-     * @return array The sorted array of objects (ascending by price)
+     * @return array<array-key, object> The sorted array of objects (ascending by price)
      */
     protected function sortByPrice(array $items): array
     {

src/BusProNet/Traits/TypeConversionTrait.php

@@ -7,6 +7,7 @@ use Carbon\Exceptions\InvalidFormatException;
 
 trait TypeConversionTrait
 {
+    /** @return list<string> */
     protected function stringToArray(?string $string, string $separator = ','): array
     {
         if (true === empty($string)) {