EventInfoMgt: Fix flake8 py3 warnings.

• unused imports
• except clause syntax
• file -> open; use binary mode for pickles

This merge request affects 1 package:

• Event/EventInfoMgt

Adding @rbianchi as watcher

added EDM master review-pending-level-1 labels

CI Result SUCCESS (hash caed6e04)

	Athena	AthSimulation
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
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 6125]

No outstanding issue, moving along with approval. -L1

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

merged

mentioned in commit a9ca3f64

added sweep:ignore label