replace include guards with pragma once

src/content/Content.hpp

@@ -1,5 +1,4 @@
-#ifndef CONTENT_CONTENT_HPP_
-#define CONTENT_CONTENT_HPP_
+#pragma once
 
 #include <memory>
 #include <optional>
@@ -230,5 +229,3 @@ public:
     const UptrsMap<std::string, ContentPackRuntime>& getPacks() const;
     const UptrsMap<std::string, rigging::SkeletonConfig>& getSkeletons() const;
 };
-
-#endif  // CONTENT_CONTENT_HPP_