Enable PHPStan

- Fix error for level 0 & 1 (level 7 has 699 errors...)
- Add `updated_at` to site_credential (so the `timestamps()` method applies correctly)

src/Wallabag/CoreBundle/Entity/SiteCredential.php

@@ -59,6 +59,13 @@ class SiteCredential
      */
     private $createdAt;
 
+    /**
+     * @var \DateTime
+     *
+     * @ORM\Column(name="updated_at", type="datetime")
+     */
+    private $updatedAt;
+
     /**
      * @ORM\ManyToOne(targetEntity="Wallabag\UserBundle\Entity\User", inversedBy="siteCredentials")
      */
@@ -178,6 +185,16 @@ class SiteCredential
         return $this->createdAt;
     }
 
+    /**
+     * Get updatedAt.
+     *
+     * @return \DateTime
+     */
+    public function getUpdatedAt()
+    {
+        return $this->updatedAt;
+    }
+
     /**
      * @return User
      */