CLN: clean warning assertions in sql tests
sorry should have merged this first, can you rebase e.g. https://dev.azure.com/pandas-dev/pandas/_build/results?buildId=64435&view=logs&j=bf526160-cc38-5046-7b49-5141c64a483a&t=6a92c4fe-2b0b-5acd-cfba-e7901042d9bd&l=57 i think there are some actual errors thanks @fangchenli 