PhpStan lvl4 related changes

- Removing unused dependencies from constructors.
- Removing other unused or write-only variables and
methods.
- Removing unnecessary checks and conditions at places
where they're not necessary.
- Fixing type-related issues.

src/Gateways/GooglePlayBilling.php

@@ -33,8 +33,6 @@ class GooglePlayBilling extends GatewayAbstract implements RecurrentPaymentInter
 
     private bool $successful = false;
 
-    private $googlePlayValidator;
-
     private $purchaseToken;
 
     public function __construct(
@@ -90,7 +88,7 @@ public function getSubscriptionExpiration(string $cid = null): \DateTime
             throw new \Exception("Missing developer notification with purchase token: [{$cid}].");
         }
 
-        $googlePlayValidator = $this->googlePlayValidator ?: $this->googlePlayValidatorFactory->create();
+        $googlePlayValidator = $this->googlePlayValidatorFactory->create();
 
         try {
             $gSubscription = $googlePlayValidator
@@ -115,7 +113,7 @@ public function charge($payment, $token): string
         }
 
         $this->purchaseToken = $developerNotification->purchase_token;
-        $googlePlayValidator = $this->googlePlayValidator ?: $this->googlePlayValidatorFactory->create();
+        $googlePlayValidator = $this->googlePlayValidatorFactory->create();
 
         try {
             $gSubscription = $googlePlayValidator
@@ -213,7 +211,7 @@ public function charge($payment, $token): string
 
     public function checkValid($token)
     {
-        $googlePlayValidator = $this->googlePlayValidator ?: $this->googlePlayValidatorFactory->create();
+        $googlePlayValidator = $this->googlePlayValidatorFactory->create();
         $developerNotification = $this->developerNotificationsRepository->findBy('purchase_token', $token);
         $this->purchaseToken = $developerNotification->purchase_token;