Update sqlite3.py to enable autocommit

as per saltstack #18152 
https://docs.python.org/2/library/sqlite3.html#sqlite3.Connection.isolation_level
addition of "isolation_level=None" to sqlite3.connect allows autocommit of "INSERT"
otherwise _connect would have to be called again with a con.commit()
Merge pull request #18213 from sumso/develop

Update sqlite3.py to enable autocommit