Bump MSRV to 1.79 (#13709)

* Bump MSRV to 1.79

This commit bumps the minimum supported rust version (MSRV) from 1.70 to
1.79. The newer rust version lets us leverage new language features in
Qiskit's rust code which will be increasingly important as we use more
rust inside of Qiskit. This commit raises the MSRV proactively to align
with the 2.0.0 release so we don't have to potentially raise it during a
minor version release (like 2.1.0 or 2.2.0) if we start using these
language features later.

* Fix 1.79 clippy warning