lint must fail on warning by default

See #3657, release log:

• 3d0146e by @yegor256: ci reconfigured
• e1c11dc by @yegor256: Merge pull request #3645 from ...
• e477279 by @yegor256: Merge pull request #3658 from ...
• 13e7eeb by @yegor256: Merge pull request #3660 from ...
• dcbf5c8 by @yegor256: #3644: master
• a1a91f4 by @yegor256: Merge branch 'master' into 364...
• d895141 by @yegor256: #3657: master
• bd41ebb by @yegor256: Merge branch 'master' into 365...
• 7e335c0 by @yegor256: #3659: master
• 05bd8d5 by @yegor256: Merge branch 'master' into 365...
• e6c55c7 by @yegor256: fix with deps
• 2f5424a by @yegor256: PhSafe in tests
• 906aaed by @yegor256: #3659: polished
• 93fba90 by @yegor256: #3659: show file
• 5b67df2 by @yegor256: #3657: fail by default
• 3dc317d by @yegor256: #3644: rm
• e10f069 by @yegor256: #3644: master
• 18b88a8 by @yegor256: Merge branch 'master' into 364...
• b17fad5 by @yegor256: Merge pull request #3654 from ...
• de9d416 by @yegor256: Merge pull request #3653 from ...
• and 34 more...

Released by Rultor 2.0-SNAPSHOT, see build log