関連ワード:  pip install opencv python error metadata generation failed    pip install opencv python error externally managed environment    pip install opencv python error    pip install opencv contrib python error    pip install opencv python syntax error    pip install opencv python == 4.5 3.56 error    pip install opencv python installing build dependencies error    pip install opencv python error subprocess exited with error    pip install opencv python getting requirements to build wheel error    pip install opencv python cmake error