CI: check diff on `Cargo.lock`

[waynexia]

Description Add CI job to check file diff of Cargo.lock.

We are tracking Cargo.lock with SCM, and should also check it in CI. An incorrect (usually is just not up-to-date) lock file won't fail a build but is annoying.

Proposal

diff lock file after cargo build. Fail if there is any diff.

Additional context