Bump actions/cache from 3 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 3 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v3...v4)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/cicd.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Cache toolchains and crates
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             ~/.rustup/settings.toml
@@ -21,7 +21,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Cache build results
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: target
           key: build-${{ runner.os }}-${{ hashFiles('**/Cargo.lock') }}