Create bot to run flake8 on new commits for the pyside projects

crmaurei has requested a bot which listens to patchset uploads in pyside repos. The bot will execute flake8 on all changed files and post inline comments respective to the errors generated by flake8.

Some rules are ignored and the maximum line columns (100) will be used as described for their official VSCode configuration: https://code.qt.io/cgit/pyside/pyside-setup.git/tree/.vscode/settings.json

--ignore=E115,E265,W503

For more information:

• https://www.flake8rules.com/rules/E115.html
• https://www.flake8rules.com/rules/E265.html
• https://www.flake8rules.com/rules/W503.html