Bump ssri from 6.0.1 to 6.0.2 (#4874)
Bump ssri from 6.0.1 to 6.0.2 (#4874)

Bumps [ssri](https://github.com/npm/ssri) from 6.0.1 to 6.0.2.
mitodl/micromasters,mitodl/micromasters,mitodl/micromasters,mitodl/micromasters