correcting the global requirements.txt

requirements.txt

-appdirs==1.4.3
-argcomplete==1.10.0
-astroid==2.2.5
-attrs==18.2.0
 black==19.3b0
-click==6.7
-cycler==0.10.0
-distro==1.4.0
-Flask==0.12.2
-isort==4.3.21
-itsdangerous==0.24
-Jinja2==2.10
-kiwisolver==1.0.1
-lazy-object-proxy==1.4.1
-MarkupSafe==1.0
-matplotlib==3.0.3
-mccabe==0.6.1
-numpy==1.16.2
-pbr==5.4.2
-pipx==0.13.2.1
-pylint==2.3.1
-pyparsing==2.4.0
-PyQt5==5.14.0
-PyQt5-sip==4.19.21
-python-dateutil==2.8.0
-six==1.12.0
-stevedore==1.30.1
-toml==0.10.0
-typed-ast==1.4.0
-userpath==1.2.0
-virtualenv==16.7.3
-virtualenv-clone==0.5.3
-virtualenvwrapper==4.8.4
-Werkzeug==0.14.1
-wrapt==1.11.2
+flake8==3.7.7
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