Looks like the error message returned by cURL changed from Failed to get url 'https://example.com': cURL error 77: error setting certificate verify locations: to Failed to get url 'https://example.com': cURL error 77: error setting certificate file:.

See https://github.com/wp-cli/wp-cli/actions/runs/12924442519/job/36043450327#step:8:97

This fixes the failing unit tests.

Note: we still have some other unrelated failing tests, see #6018