message: gltfpack: Fix output file extension for basisu
  We now output .ktx2 directly instead of .basis.
diff: @@ -113,7 +113,7 @@ bool encodeBasis(const std::string& data, const char* mime_type, std::string& re
  {
  // TODO: Support texture_scale and texture_pow2 via new -resample switch from https://github.com/BinomialLLC/basis_universal/pull/226
  TempFile temp_input(mimeExtension(mime_type));
  - TempFile temp_output(".basis");
  + TempFile temp_output(".ktx2");
  if (!writeFile(temp_input.path.c_str(), data))
  return false;
  