deps: add minimum version constraint for sqlglot to 19.9.0

[tswast]

This shouldn't be necessary, as sqlglot is only used as a transitive dependency through ibis-framework, but in setting the constraints, we can have greater assurance that sqlglot is upgraded alongside bigframes in existing environments.

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Fixes #315 🦕

[tswast]

prerelease failures appear to be due to new pandas release pandas==2.2.1. We need to fix our tests for pandas 2.2.x still (internal issue b/322845272)

[chelsea-lin]

LGTM