[9.x] Unset Connection Resolver extended callback (#41216)

* Unset Connection Resolver extended callback

* Removed isset()

* Update DatabaseManager.php

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/Database/DatabaseManager.php

@@ -396,6 +396,17 @@ public function extend($name, callable $resolver)
         $this->extensions[$name] = $resolver;
     }
 
+    /**
+     * Remove an extension connection resolver.
+     *
+     * @param  string  $name
+     * @return void
+     */
+    public function forgetExtension($name)
+    {
+        unset($this->extensions[$name]); 
+    }
+
     /**
      * Return all of the created connections.
      *