fix(detect): avoid panic with verbose flag

[rgmz]

Description:

This should fix the panic from #1141 by skipping formatting of f.Line and f.Secret for file matches, which have an empty value anyways.

It does not fix the underlying behaviour of panics being intermittently swallowed by semgroup.

gitleaks/detect/detect.go

Line 506 in 839f114

d.addFinding(finding)

Checklist:

• Does your PR pass tests?
• Have you written new tests for your changes?
• Have you lint your code locally prior to submission?

[zricethezav]

Thanks so much @rgmz, I tested this locally and I'm seeing no change in behavior. @agmond this should fix #1145