Fix Vint version detection

[letorbi]

This PR fixes the broken Vint version detection due to Python warnings that interfere with ALE's version detection algorithm.

I discovered that my Vint based Vim Script linting did not work anymore and was able to track it down to a new Python version (3.14) that has been installed on my system recently. The reason is the pkg_resources API, which is still used by the last stable Vint version (0.3.21), but has been declared as obsolete for a longer time now.

This causes vint --version to return the following:

/usr/lib/python3.14/site-packages/vint/linting/cli.py:4: UserWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html. The pkg_resources package is slated for removal as early as 2025-11-30. Refrain from using this package or pin to Setuptools<81.
  import pkg_resources
0.3.21

ALE's semver module parses this as [3, 14, 0], possibly due to python3.14 in the first line. Since ALE assumes that this version of Vint has stdin support, it calls Vint with the --stdin-display-name option, which is not yet available in Vint 0.3.21.

This PR changes the call to print Vint's version from just vint --version to PYTHONWARNINGS=ignore vint --version. This suppresses all Python warnings and thus allows ALE's semver module to detect the correct version.