Pin parking_lot_core/lock_api & resolve clippy::unnecessary_unwrap

[SteveLauC]

What does this PR do

This commit:

1. Pins indirect dependencies

   • parking_lot_core to 0.9.11
   • lock_api to 0.4.13

   by adding them to our "dev-dependencies" list. Newer versions of them
   require MSRV 1.71, which is higher than our current one 1.69.0

   parking_lot_core 0.9.12 link
   lock_api 0.4.14 link

2. Bumps bitflags to 2.4, which is required after doing 1, or we have a
   dependency conflict

3. Resolves Clippy warning "clippy::unnecessary_unwrap"

Checklist:

• I have read CONTRIBUTING.md
• I have written necessary tests and rustdoc comments
  not needed
• A change log has been added if this PR modifies nix's API
  not needed

[Copilot]

Pull Request Overview

This PR refactors error handling in the Flock drop implementation and adds dependency version constraints to maintain MSRV (Minimum Supported Rust Version) compatibility.

• Improved error handling pattern in Flock::drop using idiomatic Rust if let pattern
• Updated bitflags dependency from 2.3.3 to 2.4
• Added explicit version constraints for indirect dependencies to maintain MSRV 1.69 compatibility

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/fcntl.rs	Refactored error handling in Flock::drop to use if let Err(e) pattern instead of chaining is_err() and unwrap_err()
Cargo.toml	Updated bitflags to 2.4, added version-pinned dev-dependencies for parking_lot_core and lock_api to maintain MSRV 1.69 compatibility

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[asomers]

Hi @SteveLauC . Welcome back! BTW, did you see #2869 ? That was my attempt to fix this same problem in a different way. Unfortunately, it triggered new test failures in CI that I was never able to solve.

[SteveLauC]

Hi @SteveLauC . Welcome back!

Sorry for leaving for such a long time 🫥

did you see #2869

Sorry for didn't noticing #2689

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Recently a transitive dev-dependency published a new version that is incompatible with Nix's MSRV, causing CI to break. That's annoying, because there's really no reason why a crate's dev-dependencies ought to respect the MSRV.

Considering this, I think your approch is better, this PR is just a workaround.

I just checked that PR in details, these commits are valuable so I think we should merge them regardless of how we solve this MSRV issue:

• 4945380
• 312f460
• 646fe75

[SteveLauC]

Closing this PR in favor of #2689