Revert "added --user to installs"

[PiotrJander]

This reverts commit 14967f6.

[jakubczakon]

Mhm, now it only fails on windows due to failed tensorflow install (which I tried to fix with --user).

ERROR: Could not install packages due to an EnvironmentError: [WinError 5] Access is denied: 'c:\\hostedtoolcache\\windows\\python\\3.6.8\\x64\\lib\\site-packages\\~umpy\\.libs\\libopenblas.NOIJJG62EMASZI6NYURL6JBKM4EVBGM7.gfortran-win_amd64.dll'
2020-10-26T12:11:35.4549200Z 
2020-10-26T12:11:35.4549709Z Consider using the `--user` option or check the permissions.

[PiotrJander]

Yeah, I'm not user pip install --user is a perfect idea, especially since it doesn't work in virtual environments.

So it is left to debug why tensorflow fails - or simply Tensorflow on Windows, where this happens, until we know what causes Tensorflow to break on Windows.