Fix parsing of seven-column /proc/modules

[psfrolov]

In modern Linux distributions (e.g. Ubuntu 22.04 and newer) /proc/modules contain seven columns. The seventh column denotes module taint state.

[kellyjonbrazil]

Nice, thanks for the contribution!

[kellyjonbrazil]

Do you have test in/out files you can add to tests/fixtures/linux-proc and could you add a test case to tests/test_proc_modules.py?

[psfrolov]

Do you have test in/out files you can add to tests/fixtures/linux-proc and could you add a test case to tests/test_proc_modules.py?

I can collect input data and parsing result from Ubuntu machine for new test case

Also a question regarding existing (failed) tests: should I fix existing tests by adding taint_state: None to expected test result, or should I modify the parser code itself so to avoid taint_state in parser result object altogether if taint_state column is absent from cat /proc/modules output? (The later seems more appropriate)

[kellyjonbrazil]

Could you modify the code so taint_state only shows up if it exists? Thanks!

[kellyjonbrazil]

@psfrolov could you make the change above and add tests? Thanks!