Fail on edition 2021 (due to caching)

[MarcoIeni]

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Description

When updating to rust 2021 edition we get this error due to the fact that the cargo audit action is using the previous version of cargo.

Workflow code

https://github.com/TrueLayer/ginepro/blob/c6df27b7db64e64227dcaca6ec4d2c45d9db8f3e/.github/workflows/audit.yml

Action output

Run actions-rs/audit-check@v1
  with:
    token: ***
/usr/share/rust/.cargo/bin/cargo generate-lockfile
error: failed to load manifest for workspace member `/home/runner/work/ginepro/ginepro/ginepro`

Caused by:
  failed to parse manifest at `/home/runner/work/ginepro/ginepro/ginepro/Cargo.toml`

Caused by:
  feature `edition2021` is required

  The package requires the Cargo feature called `edition2021`, but that feature is not stabilized in this version of Cargo (1.55.0 (32da73ab1 2021-08-23)).
  Consider trying a newer version of Cargo (this may require the nightly release).
  See https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#edition-2021 for more information about the status of this feature.
Error: The process '/usr/share/rust/.cargo/bin/cargo' failed with exit code 101

Expected behavior

Cargo audit action uses the latest version of cargo if available.

[MarcoIeni]

Installing the toolchain before running the action fixed it: