support `PRAGMA foreign_keys`

[ipmb]

Originally filed here libsql/sqld#287

The following SQL fails with this error using ibsql-experimental-python 0.0.25 and sqld 0.22.0.

   File "/home/runner/work/django-libsql/django-libsql/django_repo/django/db/backends/sqlite3/base.py", line 227, in disable_constraint_checking
    enabled = cursor.execute("PRAGMA foreign_keys").fetchone()[0]
ValueError: invalid column type

This code comes from Django's sqlite3 backend: https://github.com/django/django/blob/9c5e382b981608a26f2c55f1259d9e823fee5f15/django/db/backends/sqlite3/base.py#L238-L245