Soundness issues in sub-dependency `sized-chunks` (via `sentry`, `im` crates)

[RUSTSEC-2020-0041](https://rustsec.org/advisories/RUSTSEC-2020-0041.html)

Rel issues:
*  https://github.com/bodil/sized-chunks/issues/11
*  https://github.com/getsentry/sentry-rust/issues/258