Pip: PyYamlをインストールできません：UnicodeDecodeError： 'utf-8'コーデックは69番目のバイト0xc6をデコードできません：無効な継続バイト

• Pipバージョン：9.0.1
• Pythonバージョン：3.6.4
• オペレーティングシステム：Windows、64ビット

説明：

Installing collected packages: PyYAML
  Running setup.py install for PyYAML ... error
Exception:
Traceback (most recent call last):
  File "c:\users\nathan\appdata\local\programs\python\python36-32\lib\site-packages\pip\compat\__init__.py", line 73, in console_to_str
    return s.decode(sys.__stdout__.encoding)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc6 in position 69: invalid continuation byte

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:\users\nathan\appdata\local\programs\python\python36-32\lib\site-packages\pip\basecommand.py", line 215, in main
    status = self.run(options, args)
  File "c:\users\nathan\appdata\local\programs\python\python36-32\lib\site-packages\pip\commands\install.py", line 342, in run
    prefix=options.prefix_path,
  File "c:\users\nathan\appdata\local\programs\python\python36-32\lib\site-packages\pip\req\req_set.py", line 784, in install
    **kwargs
  File "c:\users\nathan\appdata\local\programs\python\python36-32\lib\site-packages\pip\req\req_install.py", line 878, in install
    spinner=spinner,
  File "c:\users\nathan\appdata\local\programs\python\python36-32\lib\site-packages\pip\utils\__init__.py", line 676, in call_subprocess
    line = console_to_str(proc.stdout.readline())
  File "c:\users\nathan\appdata\local\programs\python\python36-32\lib\site-packages\pip\compat\__init__.py", line 75, in console_to_str
    return s.decode('utf_8')
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc6 in position 69: invalid continuation byte

私が実行したもの：

git clone https://github.com/ritiek/spotify-downloader
cd .\spotify-downloader
pip3 install -U -r requirements.txt