Fixed claim check in JwtValidator

* Removed the addRequiredClaimWithValue() method, as checking
  the value should be up to the implementation.

src/Validator/JwtValidator.php

@@ -21,12 +21,10 @@ class JwtValidator
 
     public function addRequiredClaim(string $name)
     {
-        $this->requireClaims[$name] = true;
-    }
-
-    public function addRequiredClaimWithValue(string $name, $value)
-    {
-        $this->requireClaims[$name] = [ $value ];
+        if (!in_array($name, $this->requireClaims)) {
+            return;
+        }
+        $this->requireClaims[] = $name;
     }
 
     public function validateToken(JwtToken $token)