New release for eo-0.38.1

[maxonfjvipon]

New release for eo-0.38.1

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PR-Codex overview

This PR updates the version to 0.38.1, adds tests to various packages, and improves object documentation.

Detailed summary

• Updated version to 0.38.1 in multiple files
• Added tests to several packages
• Enhanced object documentation with GitHub links

The following files were skipped due to too many changes: tests/org/eolang/rust-tests.eo

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