Bump xmlunit.version from 2.2.1 to 2.8.2 (#5180)

Bumps `xmlunit.version` from 2.2.1 to 2.8.2.

Updates `xmlunit-core` from 2.2.1 to 2.8.2
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/main/RELEASE_NOTES.md)
- [Commits](https://github.com/xmlunit/xmlunit/compare/v2.2.1...v2.8.2)

Updates `xmlunit-matchers` from 2.2.1 to 2.8.2
- [Release notes](https://github.com/xmlunit/xmlunit/releases)
- [Changelog](https://github.com/xmlunit/xmlunit/blob/main/RELEASE_NOTES.md)
- [Commits](https://github.com/xmlunit/xmlunit/compare/v2.2.1...v2.8.2

)

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