Allow sqlglot library v29.x - v30.x

[rolandwalker]

Description

The previous issues in CI were likely a transient PyPi issue.

Checklist

• I added this contribution to the changelog.md file.
• I added my name to the AUTHORS file (or it's already there).
• To lint and format the code, I ran

  uv run ruff check && uv run ruff format && uv run mypy --install-types .

[github-actions]

Findings

1. Correctness regression: declared version range is wrong
   In pyproject.toml:17, sqlglot[c] ~= 29.0.1 means >=29.0.1,<30.0.0, so this PR does not allow 30.x.
   That conflicts with both the PR title/body and changelog.md:6, and will break installs expecting 30.x compatibility.

   • Action: change to an explicit two-major range, e.g. sqlglot[c] >=29.0.1,<31.0.0 (or equivalent).

2. Missing coverage for the claimed compatibility window
   This PR changes dependency bounds but adds no validation for both ends of the range.

   • Action: add CI matrix checks for at least latest 29.x and latest 30.x to catch bound/spec mistakes like this.

No direct security issues found in this diff.

[rolandwalker]

Nope, not a transient issue. We apparently should commit to sqlglot 30.x.