Don't automatically show completions when cursor is over number literals

[ankoh]

We currently are not checking the symbol type below the cursor. We should not show the autocompletion prompt automatically if we're on top of number literals.

https://github.com/ankoh/sqlynx/assets/3986510/d4036160-5d0e-44f9-a7a9-601fba4da14c

Reported by @vogelsgesang