Deps: Bump actions/cache in /setup-rust in the dependencies group

Bumps the dependencies group in /setup-rust with 1 update: [actions/cache](https://github.com/actions/cache).


Updates `actions/cache` from 5.0.5 to 6.0.0
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@27d5ce7...2c8a9bd)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

setup-rust/action.yml

@@ -11,7 +11,7 @@ inputs:
 runs:
   using: "composite"
   steps:
-    - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
+    - uses: actions/cache@2c8a9bd7457de244a408f35966fab2fb45fda9c8 # v6.0.0
       with:
         path: |
           ~/.cargo/bin/