vertex indices are unsigned, so make them unsigned to stop the linter being sad

include/fggl/data/model.hpp

@@ -119,7 +119,7 @@ namespace fggl::data {
 				return m_index.size();
 			}
 
-			inline Vertex &vertex(int idx) {
+			inline Vertex &vertex(uint32_t idx) {
 				return m_verts[idx];
 			}