Fix nullable deprecations

Author: lgeorget

Form/HCaptchaType.php

@@ -40,7 +40,7 @@ class HCaptchaType extends AbstractType
      * If the site key is not set globally by configuration, then it must be
      * passed as an option to the form type.
      */
-    public function __construct(HCaptchaValueFetcher $hcaptchaValueFetcher, string $hcaptchaSiteKey = null)
+    public function __construct(HCaptchaValueFetcher $hcaptchaValueFetcher, ?string $hcaptchaSiteKey = null)
     {
         $this->valueFetcher = $hcaptchaValueFetcher;
         $this->hcaptchaSiteKey = $hcaptchaSiteKey;

Service/HCaptchaVerifier.php

@@ -68,7 +68,7 @@ class HCaptchaVerifier
      */
     public function __construct(ClientInterface $client,
         RequestFactoryInterface $requestFactory, StreamFactoryInterface $streamFactory,
-        string $hcaptchaSecret, LoggerInterface $logger = null)
+        string $hcaptchaSecret, ?LoggerInterface $logger = null)
     {
         $this->client = $client;
         $this->requestFactory = $requestFactory;
@@ -93,7 +93,7 @@ public function __construct(ClientInterface $client,
      * @throws BadAnswerFromHCaptchaException Thrown if the HCaptcha API has
      * failed to answer in due time or if the answer is out of specification.
      */
-    public function verify(HCaptchaResponse $value, string &$output = null): bool
+    public function verify(HCaptchaResponse $value, ?string &$output = null): bool
     {
         // Make the validation request to hCaptcha
         $stream = $this->streamFactory->createStream(