fix: Exempt LTI in safe-sessions enforcement
fix: Exempt LTI in safe-sessions enforcement

This LTI call was failing in unit tests when `ENFORCE_SAFE_SESSIONS` was
enabled. I'm not sure why we didn't see failures in production when the
toggle was enabled in config.

eduNEXT/edx-platform,angelapper/edx-platform,angelapper/edx-platform,eduNEXT/edx-platform,arbrandes/edx-platform,eduNEXT/edx-platform,arbrandes/edx-platform,eduNEXT/edx-platform,arbrandes/edx-platform,arbrandes/edx-platform,angelapper/edx-platform,angelapper/edx-platform