Fix sqlite:pysqlite warning

[elephantum]

/datapipe/store/database.py:63: SAWarning: Dialect sqlite:pysqlite will not make use of SQL compilation caching as it does not set the 'supports_statement_cache' attribute to True. This can have significant performance implications including some performance degradations in comparison to prior SQLAlchemy versions. Dialect maintainers should seek to set this attribute to True after appropriate development and testing for SQLAlchemy 1.4 caching support. Alternatively, this attribute may be set to False which will disable this warning. (Background on this warning at: https://sqlalche.me/e/20/cprf)
con.execute(text("PRAGMA journal_mode=WAL"))