(fix) cqltypes: fix SyntaxWarning for invalid escape sequence in UDT names

[mykaul]

In cqltype_to_python(), double-quoted UDT names containing backslashes (e.g. '"!@#$%^&*()[]\ frozen >>>") were passed to ast.literal_eval without escaping, producing SyntaxWarning on Python 3.12+:

SyntaxWarning: "\ " is an invalid escape sequence

Escape backslashes before wrapping the token for ast.literal_eval. The reverse operation already exists in python_to_cqltype() at line 159.

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• [] I added relevant tests for new features and bug fixes.
• All commits compile, pass static checks and pass test.
• PR description sums up the changes and reasons why they should be introduced.
• I have provided docstrings for the public items that I want to introduce.
• I have adjusted the documentation in ./docs/source/.
• I added appropriate Fixes: annotations to PR description.

[Copilot]

Pull request overview

This PR hardens the CQL type parsing utilities to avoid SyntaxWarning when parsing escaped CQL identifiers that contain backslashes, and adds a regression test to ensure the warning does not recur.

Changes:

• Escape backslashes when converting escaped, double-quoted CQL tokens into a Python literal for ast.literal_eval().
• Add a unit test that asserts cqltype_to_python() does not emit SyntaxWarning and that python_to_cqltype() round-trips the parsed structure.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
cassandra/cqltypes.py	Escapes backslashes in escaped-quoted identifier tokens before ast.literal_eval() to prevent invalid-escape SyntaxWarning.
tests/unit/test_metadata.py	Adds a regression test covering backslash-containing escaped identifiers and round-trip behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

This PR updates the CQL type string <-> Python representation conversion helpers to correctly handle quoted identifiers containing backslashes and single quotes, and adds unit tests to prevent regressions.

Changes:

• Escape backslashes and single quotes in cqltype_to_python() to avoid SyntaxWarning/parsing issues during ast.literal_eval.
• Unescape \' in python_to_cqltype() to support round-tripping identifiers containing '.
• Add unit tests covering backslash-containing identifiers (no SyntaxWarning) and single-quote-containing identifiers (parse + round-trip).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
cassandra/cqltypes.py	Adjusts escaping/unescaping in cqltype_to_python and python_to_cqltype for quoted identifiers.
tests/unit/test_metadata.py	Adds regression tests for backslash/single-quote handling and round-trip behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.