Make pre-commit run Bandit hook using a single process

[Klavionik]

I would like you to consider this small change to the pre-commit manifest.

Currently pre-commit may run Bandit hook with multiple processes, which can lead to Bandit generating multiple reports from these runs. It's only a bit confusing when you run Bandit for the first time on a moderately large database and output report on the screen, but it's much worse if you're saving your report to, let's say, an HTML file. Then you would get a straight wrong report.

This is what happens, when I run the same Bandit command with pre-commit and without it on the same codebase:

(pre-commit)

(w/o pre-commit)

Each run just overwrites the report file, and in the end we're left with what happens to be the latest run result.

One can mitigate this problem by using the -r flag and setting pre-commit pass_filenames option to false, but this doesn't suit everyone (or should be at least documented).

[ericwb]

LGTM