Remove flake8 config + flake8 CI #101

Job	Run time
Build plugins 🏗 / Generate matrix	6s
Build plugins 🏗 / Build _meta 🛠	50s
Build plugins 🏗 / Build citadel 🛠	55s
Build plugins 🏗 / Build cloud_captchas 🛠	1m 39s
Build plugins 🏗 / Build livesync 🛠	57s
Build plugins 🏗 / Build livesync_debug 🛠	58s
Build plugins 🏗 / Build owncloud 🛠	1m 33s
Build plugins 🏗 / Build payment_manual 🛠	48s
Build plugins 🏗 / Build payment_paypal 🛠	50s
Build plugins 🏗 / Build payment_sixpay 🛠	50s
Build plugins 🏗 / Build piwik 🛠	1m 39s
Build plugins 🏗 / Build previewer_code 🛠	55s
Build plugins 🏗 / Build previewer_jupyter 🛠	1m 44s
Build plugins 🏗 / Build prometheus 🛠	54s
Build plugins 🏗 / Build storage_s3 🛠	48s
Build plugins 🏗 / Build themes_legacy 🛠	1m 27s
Build plugins 🏗 / Build ursh 🛠	1m 30s
Build plugins 🏗 / Build vc_dummy 🛠	1m 2s
Build plugins 🏗 / Build vc_zoom 🛠	1m 27s
Bundle wheels 📦	13s
	21m 5s

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