pymssql 2.3.13 bundles FreeTDS 1.4.26, which fixes known segfault
issues in TLS negotiation and connection handling present in FreeTDS
1.3.17 (the version provided by Debian Bookworm's apt repos).

Also removes pymssql from no-build-isolation-package so that uv uses
the official pre-built wheel (with bundled FreeTDS) rather than
compiling from source against the older system FreeTDS headers.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>