add -W argument to ignore warnings

[Randomneo]

sometimes you'd like to ignore warnings but there is no argument for it. WDYT

[wbolster]

not opposed to the idea itself, but what should this do?

  --disable-warnings, --disable-pytest-warnings
                        Disable warnings summary

or

pytest-warnings:
  -W PYTHONWARNINGS, --pythonwarnings=PYTHONWARNINGS
                        Set which warnings to report, see -W option of Python
                        itself

?

also, ‘disable’ has a typo

[Randomneo]

fixed typos. I assume it should do the second one -W PYTHONWARNINGS.

Should I change description from disable warnings to ignore warnings?

Also changed arg to make it more obvious

[wbolster]

thanks, merged with a few tiny tweaks! 🚀