GoodRunsLists: Python 3 / flake8 fixes

Updates for python 3 compatibility. Enable flake8 checking and fix warnings.

This merge request affects 1 package:

• DataQuality/GoodRunsLists

added DQ master review-pending-level-1 labels

CI Result SUCCESS (hash ee2d15cc)

	Athena	AthSimulation	AnalysisBase
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 11212]

Looks good and CI clean, approving (L1)

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 4de99955

added sweep:ignore label