Quando tento instalar aparece isso:
Microsoft Windows [versão 10.0.17134.648]
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C:\Users\LeSal>pip install pytest
Requirement already satisfied: pytest in c:\users\lesal\appdata\roaming\python\python37\site-packages (4.4.0)
Requirement already satisfied: more-itertools>=4.0.0; python_version > "2.7" in c:\users\lesal\appdata\roaming\python\python37\site-packages (from pytest) (7.0.0)
Requirement already satisfied: py>=1.5.0 in c:\users\lesal\appdata\roaming\python\python37\site-packages (from pytest) (1.8.0)
Requirement already satisfied: attrs>=17.4.0 in c:\users\lesal\appdata\roaming\python\python37\site-packages (from pytest) (19.1.0)
Requirement already satisfied: atomicwrites>=1.0 in c:\users\lesal\appdata\roaming\python\python37\site-packages (from pytest) (1.3.0)
Requirement already satisfied: six>=1.10.0 in c:\users\lesal\appdata\roaming\python\python37\site-packages (from pytest) (1.12.0)
Requirement already satisfied: setuptools in c:\program files (x86)\python37-32\lib\site-packages (from pytest) (40.6.2)
Requirement already satisfied: pluggy>=0.9 in c:\users\lesal\appdata\roaming\python\python37\site-packages (from pytest) (0.9.0)
Requirement already satisfied: colorama; sys_platform == "win32" in c:\users\lesal\appdata\roaming\python\python37\site-packages (from pytest) (0.4.1)