fix env serialization

Author: giancarloromeo

packages/pytest-simcore/src/pytest_simcore/minio_service.py

@@ -34,5 +34,7 @@ def minio_s3_settings_envs(
     minio_s3_settings: S3Settings,
     monkeypatch: pytest.MonkeyPatch,
 ) -> EnvVarsDict:
-    changed_envs: EnvVarsDict = minio_s3_settings.model_dump(exclude_unset=True)
+    changed_envs: EnvVarsDict = minio_s3_settings.model_dump(
+        mode="json", exclude_unset=True
+    )
     return setenvs_from_dict(monkeypatch, changed_envs)