let's remove the `XSD` interface and add the `validate()` method to `XML`

See #276, release log:

• 9cb87a1 by @yegor256: #338 common-lang up
• 6a7b793 by @yegor256: Merge pull request #275 from j...
• b08adb3 by @yegor256: #276 .validate() added
• c996da7 by @renovate[bot]: fix(deps): update dependency o...
• 2296cff by @renovate[bot]: fix(deps): update dependency c...
• 54eca04 by @yegor256: #272 disable tests
• c3c31b8 by @yegor256: #272 url
• 9a79404 by @yegor256: #272 polish
• d96e331 by @yegor256: #272 java version
• 65e46fd by @yegor256: #272 test for utf
• 34f5712 by @yegor256: Merge pull request #271 from j...
• b5049d8 by @renovate[bot]: chore(deps): update yegor256/c...

Released by Rultor 2.0-SNAPSHOT, see build log