support PHP 8.0

Author: bshaffer

src/Key.php

@@ -3,6 +3,7 @@
 namespace Firebase\JWT;
 
 use InvalidArgumentException;
+use OpenSSLAsymmetricKey;
 
 class Key
 {
@@ -18,9 +19,18 @@ class Key
      */
     public function __construct($keyMaterial, $algorithm)
     {
-        if (!(is_string($keyMaterial) || is_resource($keyMaterial)) || empty($keyMaterial)) {
-            throw new InvalidArgumentException('Type error: $keyMaterial must be a string');
+        if (
+            !is_string($keyMaterial)
+            && !is_resource($keyMaterial)
+            && !$keyMaterial instanceof OpenSSLAsymmetricKey
+        ) {
+            throw new InvalidArgumentException('Type error: $keyMaterial must be a string, resource, or OpenSSLAsymmetricKey');
         }
+
+        if (empty($keyMaterial)) {
+            throw new InvalidArgumentException('Type error: $keyMaterial must not be empty');
+        }
+
         if (!is_string($algorithm)|| empty($keyMaterial)) {
             throw new InvalidArgumentException('Type error: $algorithm must be a string');
         }