CaloMonitoring: Python 3 / flake8 fixes

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

This merge request affects 1 package:

• Calorimeter/CaloMonitoring

Adding @pavol as watcher

added Calorimeter JetEtmiss master review-pending-level-1 labels

CI Result SUCCESS (hash 1cb4fbb2)

	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 11782]

The changes look good, and CI passes. Approving.

Xiaozhong (L1)

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

merged

mentioned in commit bfa9ce17

added sweep:ignore label