Deployment failing because of `caching_sha2_password` change

[swissspidy]

In https://github.com/wp-cli/wp-cli-tests/pull/220, we replaced mysql_native_password with caching_sha2_password.

That seemed to work fine everywhere, but there are warnings & thus failures in the deployment step.

See https://github.com/wp-cli/wp-cli-bundle/actions/runs/11257982684/job/31305127211#step:15:218 and https://github.com/wp-cli/wp-cli-tests/issues/226