Fix: use CONCAT with CAST to create interval for DATETIME_ADD

[flybitcone]

Change the interval and CROSS JOIN function

[flybitcone]

The check is not pass may be due to the Python version in the test environment.

Pls check the error in detain:
Run actions/setup-python@v2
Version 3.7 was not found in the local cache
Error: Version 3.7 with arch x64 not found

Thanks.

[Chessing234]

this file is marked auto-generated — usually you want to fix the bigquery source and re-transpile rather than hand-edit concepts_postgres. also the patch drops the mimiciv_derived. schema and brings in GENERATE_ARRAY / DATETIME_ADD, which won't run as plain postgres. if the goal is interval construction, maybe keep GENERATE_SERIES + + INTERVAL '1' HOUR like the current transpiled version?