rename 'files' to 'io'

test/coders/vec3.cpp

@@ -1,12 +1,12 @@
 #include <gtest/gtest.h>
 
 #include "coders/vec3.hpp"
-#include "files/files.hpp"
+#include "io/io.hpp"
 
 TEST(VEC3, Decode) {
     auto file = std::filesystem::u8path(
         "res/models/block.vec3"
     );
-    auto bytes = files::read_bytes_buffer(file);
+    auto bytes = io::read_bytes_buffer(file);
     auto model = vec3::load(file.u8string(), bytes);
 }