chore(doc): update clippy in core/CONTRIBUTING.md to align ci

[Svecco]

Which issue does this PR close?

Close N/A

Originally in ./.github/workflows/ci_core.yml:78::

- name: Cargo clippy
  working-directory: core
  run: cargo clippy --workspace --all-targets --all-features -- -D warnings

But in ./core/CONTRIBUTING.md:7::

- `cargo clippy` to catch common mistakes and improve code.

cc @Xuanwo

Other columns: As Title/None.

[Xuanwo]

Hi, it's somewhat expected, as it can be quite challenging for contributors to get --all-features working.

[Svecco]

Hi, it's somewhat expected, as it can be quite challenging for contributors to get --all-features working.

Okay, got it👌