deps: update rustls to 0.23.46

[Jaro-c]

Summary

• The scheduled audit has failed on main and develop since 2026-10-15 because rustls 0.23.45 carries RUSTSEC-2026-0346, -0347, -0348 and -0349. All four are fixed in 0.23.46.
• This is the lockfile bump and nothing else.

Changes

• Cargo.lock: rustls 0.23.45 to 0.23.46 (cargo update -p rustls).

rustls reaches podup only through ureq, in the self-update download.

Test plan

• cargo test --locked --all-features --workspace passes locally: 43 test targets, none failing
• cargo deny check advisories reports ok, and cargo audit finds nothing, on this lockfile
• The scheduled audit goes green on main and develop after this lands (main needs the release pull request)

I did not run fmt, clippy or the shell tests: the diff touches no source file.

Related issues

Refs #2047. I will close it once the scheduled audit is green on both branches.