exists is a method, so prior to change, assert would always pass

thankfully, this still works on sqlalchemy 1.4 after change

seems that table.table.exists() actually created table

if we replace it with self.db_has_table instead, it doesn't work
I assume because it works on sqlalchemy metadata level and not issuing actual sql engine commands

to demonstrate that I've put the asserts with self.db.has_table in setUp method

for now just removed the assert from test_create_table_shorthand* tests

passes all tests on sqlalchemy 1.4

all tests passed