Fix linter errors in bulk edit script

[PassionateBytes]

This PR addresses linting failures like this one, which have been observed in recent CI jobs.

Observed Errors:

$ invoke lint
.../contrib/bulk_edit/timetagger_bulk_edit.py:163:20: F821 undefined name 'binascii'
.../contrib/bulk_edit/timetagger_bulk_edit.py:289:17: F841 local variable 'e' is assigned to but never used
Error: Process completed with exit code 1.

Changes:

• Add missing import statement for undefined reference to binascii.
• Remove unused variable e.

Result:

$ invoke lint
No style errors found

Edit: As evidenced by the successful CI run on this PR (see below), the linter error is resolved.