问错误无法为xmlsec构建轮子，这是安装基于pyproject.toml的项目所必需的。

EN

  Building wheels for collected packages: xmlsec
  Building wheel for xmlsec (pyproject.toml) ... error
  ERROR: Command errored out with exit status 1:
  Complete output (14 lines):
  running bdist_wheel
  running build
  running build_py
  package init file 'src/xmlsec/__init__.py' not found (or not a regular file)
  creating build
  creating build/lib.macosx-10.9-x86_64-3.7
  creating build/lib.macosx-10.9-x86_64-3.7/xmlsec
  copying src/xmlsec/py.typed -> build/lib.macosx-10.9-x86_64-3.7/xmlsec
  copying src/xmlsec/tree.pyi -> build/lib.macosx-10.9-x86_64-3.7/xmlsec
  copying src/xmlsec/__init__.pyi -> build/lib.macosx-10.9-x86_64-3.7/xmlsec
  copying src/xmlsec/constants.pyi -> build/lib.macosx-10.9-x86_64-3.7/xmlsec
  copying src/xmlsec/template.pyi -> build/lib.macosx-10.9-x86_64-3.7/xmlsec
  running build_ext
  error: Unable to invoke pkg-config.
  ----------------------------------------
  ERROR: Failed building wheel for xmlsec
Failed to build xmlsec
ERROR: Could not build wheels for xmlsec, which is required to install pyproject.toml-based projects