update rand to 0.10 and rand_distr to 0.6

[CanReader]

What this changes

Bumps rand to 0.10 and rand_distr to 0.6 together and ports src/rng.rs to the new names (from_entropy -> make_rng, gen_range -> random_range, gen -> random, Rng -> RngExt).

Why

Replaces #34 and #32. The two crates have to move at the same time, rand_distr 0.6 is built on rand 0.10, so each dependabot PR failed on its own.

Heads up for the next release: with_rng hands out a rand 0.10 StdRng, so this is a breaking change for anyone using it with rand 0.8 traits. Seeded runs also produce different numbers than 0.3.0 did, same seed but a different generator underneath.

How it was verified

• cargo test passes
• cargo clippy --all-targets -- -D warnings is clean
• cargo check on 1.87 with a fresh lockfile