- update to 3.17.6:
* Fix bug in recursive `model.delete_instance()` when a table
contains foreign-keys at multiple depths of the graph
* Fix regression in pool behavior on systems where
`time.time()` returns identical values for two connections.
This adds a no-op comparable sentinel to the heap to prevent
any recurrence of this problem.
* Ensure that subqueries inside `CASE` statements generate
correct SQL.
* Fix regression that broke server-side cursors with Postgres
* Fix to ensure compatibility with psycopg3 - the libpq
TransactionStatus constants are no longer available on the
`Connection` instance.
* Fix quoting issue in pwiz that could generate invalid python
code for double-quoted string literals used as column defaults.