Follow interface signature

src/Encoder/CsvEncoder.php

@@ -85,7 +85,7 @@ class CsvEncoder implements EncoderInterface, DecoderInterface {
    *
    * Uses HTML-safe strings, with several characters escaped.
    */
-  public function encode($data, string $format, array $context = []):string {
+  public function encode(mixed $data, string $format, array $context = []): string {
     switch (gettype($data)) {
       case "array":
         break;
@@ -260,7 +260,7 @@ class CsvEncoder implements EncoderInterface, DecoderInterface {
    * @throws \League\Csv\Exception
    * @throws \League\Csv\Exception
    */
-  public function decode($data, string $format, array $context = []) {
+  public function decode(string $data, string $format, array $context = []): mixed {
     $csv = Reader::createFromString($data);
     $csv->setDelimiter($this->delimiter);
     $csv->setEnclosure($this->enclosure);