fix(deps): update dependency com.yegor256:xsline to v0.21.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
com.yegor256:xsline	0.20.1 -> 0.21.0

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Release Notes

yegor256/xsline

### [`v0.21.0`](https://togithub.com/yegor256/xsline/releases/tag/0.21.0): StFailure [Compare Source](https://togithub.com/yegor256/xsline/compare/0.20.1...0.21.0) See [#​75](https://togithub.com/yegor256/xsline/issues/75), release log: - [`1b541dc`](https://togithub.com/yegor256/xsline/commit/1b541dc096f2de256d80e2f714a65b2b91f9e39d) by [@​yegor256](https://togithub.com/yegor256): [#​75](https://togithub.com/yegor256/xsline/issues/75) year up - [`86f7405`](https://togithub.com/yegor256/xsline/commit/86f7405ed00a074045ae92618786bc6c2cef63c9) by [@​yegor256](https://togithub.com/yegor256): [#​75](https://togithub.com/yegor256/xsline/issues/75) StFailure - [`c9d2547`](https://togithub.com/yegor256/xsline/commit/c9d2547204285d4fa7491d7532279c5f21ef2a90) by [@​renovate](https://togithub.com/renovate)\[bot]: Update dependency com.jcabi:pa... - [`89bcab2`](https://togithub.com/yegor256/xsline/commit/89bcab21dfbfa1de52045dcc91951766766a7275) by [@​renovate](https://togithub.com/renovate)\[bot]: Update dependency com.jcabi:jc... Released by Rultor 2.0-SNAPSHOT, see [build log](https://www.rultor.com/t/30752-1473262507)

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[yegor256]

@rultor please, try to merge

[rultor]

@rultor please, try to merge

@yegor256 OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor please, try to merge

@yegor256 Done! FYI, the full log is here (took me 56min)