[56_maintenance] Fix cargo_audit: Pin cargo-msrv and Cargo.lock in CI

[alamb]

NOTE: almost all of this PR is Cargo.lock files. I swear it is easy to review...

• Part of Release arrow-rs / parquet Patch version 56.2.1 (May 2026) #9857
• Follow-up to [56_maintenance] Prevent BitChunks length overflow (#9818) #9896

Rationale

The MSRV check is failing on 56 (I saw on #989) due to the fact that many of arrow's dependencies have upgraded to a newer version of rust that has a newer MSRV.

Here is an example CI fail https://github.com/apache/arrow-rs/actions/runs/25373570591/job/74402867748?pr=9896

  Run if which cargo-msrv ; then echo "using existing cargo-msrv binary" ; else cargo
  install cargo-msrv ; fi
    if which cargo-msrv ; then echo "using existing cargo-msrv binary" ; else cargo install
  cargo-msrv ; fi
    shell: sh -e {0}
    env:
      RUSTFLAGS: -C debuginfo=1
      RUST_BACKTRACE: 1
      Updating crates.io index
  error: cannot install package `cargo-msrv 0.19.3`, it requires rustc 1.91.1 or newer,
  while the currently active rustc version is 1.89.0
  `cargo-msrv 0.18.4` supports rustc 1.85
  Error: Process completed with exit code 101.

This PR:

• Pins cargo-msrv in the 56_maintenance MSRV CI job to a version compatible with the Rust toolchain used by the job
• Checks in a Cargo.lock file so the older versions of the crate still run

Note this doesn't actually change any code in this crate. It simply updates the CI enough to get the tests to pass

[alamb]

Thank you @viirya