Add pylint3 to the ci

  - apt-get -qqy install --no-install-recommends python3-bandit

  - bandit -r ./libmat2 --format txt --skip B101,B404,B603,B405,B314

pylint:

  stage: linting

  script:

  - apt-get -qqy update

  - apt-get -qqy install --no-install-recommends pylint3 python3-mutagen python3-gi-cairo gir1.2-poppler-0.18 gir1.2-gdkpixbuf-2.0

  - pylint3 --extension-pkg-whitelist=cairo,gi ./libmat2

pyflakes:

  stage: linting

  script:

[FORMAT]

good-names=e,f,i,x,s

max-locals=20

[MESSAGES CONTROL]

disable=

    fixme,

    invalid-name,

    missing-docstring,

    protected-access,

		abstract-method,

		wrong-import-position,

		catching-non-exception,

		cell-var-from-loop,

		locally-disabled,

		invalid-sequence-index,  # pylint doesn't like things like `Tuple[int, bytes]` in type annotation