Improve repr(Skipped): add __repr__ method and test coverage

[Artem-Sarkisian]

This PR enhances the Skipped exception by implementing a repr method, ensuring a more informative and structured representation when debugging.

Changes:
• Implemented repr method for Skipped, improving its debuggability.
• Added a test to verify repr(Skipped(...)) output.
• Created a changelog entry (12647.improvement.rst) for better traceability.

Checklist:
• Added a test for the new behavior.
• Created a new changelog file (12647.improvement.rst).
• Updated documentation (not required for this change).
• Allow maintainers to squash and merge commits.

Closes #12647

[RonnyPfannschmidt]

How does diverging from the common default for exceptions concretely enhance debugging

[Artem-Sarkisian]

How does diverging from the common default for exceptions concretely enhance debugging

The issue #12647 was created to address the need for improving the debugging experience when working with skipped tests in pytest. The default behavior for Skipped exceptions in pytest did not provide enough detail about why a test was skipped, which led to difficulties in debugging and understanding the root cause of skipped tests. The change proposed in this PR—adding a custom repr method to the Skipped exception—was aimed at enhancing this situation by providing more informative and structured exception output.

By implementing this change, we ensure that debugging skipped tests is more efficient, as developers can now see the exact reason for a skip directly in the exception message. This improvement was directly motivated by the concerns raised in issue #12647 and addresses the usability of pytest in real-world scenarios.

[The-Compiler]

I'm confused. The issue you mention (also as "Closes:" in the PR description, as well as in the changelog) seems to be entirely unrelated to what this PR does?