Implicit conversion from float to int Warning (#192)

Fixes WARNING - Implicit conversion from float 89.99998842592592 to int loses precision in (...)/spatie/ssl-certificate/src/SslCertificate.php on line 165

src/SslCertificate.php

@@ -162,7 +162,7 @@ public function expirationDate(): Carbon
 
     public function lifespanInDays(): int
     {
-        return $this->validFromDate()->diffInDays($this->expirationDate(), false);
+        return (int)$this->validFromDate()->diffInDays($this->expirationDate(), false);
     }
 
     public function isExpired(): bool