This way, when Mbed TLS's `analyze_outcomes.py` loads the python module from
TF-PSA-Crypto (because it needs to know the value of `INTERNAL_TEST_CASES`),
there's no risk that the subproject and the superproject will have different
requirements on auxiliary modules such as `mbedtls_framework.outcome_analysis`.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>