Style: Replace header guards with #pragma once

include/godot_cpp/core/mutex_lock.hpp

@@ -28,8 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
-#ifndef GODOT_MUTEX_LOCK_HPP
-#define GODOT_MUTEX_LOCK_HPP
+#pragma once
 
 #include <godot_cpp/classes/mutex.hpp>
 
@@ -55,5 +54,3 @@ public:
 #define _THREAD_SAFE_UNLOCK_ _thread_safe_.unlock();
 
 } // namespace godot
-
-#endif // GODOT_MUTEX_LOCK_HPP