update lint target in tox.ini

[tiran]

    # tox doesn't expand *.py and pylint treats ./tests/ as a package
    {envpython} -m pylint -d c,r,i,W0613 -r n --notes= --disable=star-args \
        tests/conftest.py \
        tests/functional/base.py \
        tests/functional/__init__.py \
        tests/functional/test_basics.py \
        tests/functional/test_container.py \
        tests/functional/test_key.py \
        tests/test_authenticators.py \
        tests/test_cli.py \
        tests/test_custodia.py \
        tests/test_httpd.py \
        tests/test_ipa.py \
        tests/test_message_kem.py \
        tests/test_misc.py \
        tests/test_plugins.py \
        tests/test_secrets.py \
        tests/test_server.py \
        tests/test_store.py \
        tests/test_store_sqlite.py