ci: Bump Swatinem/rust-cache from 1 to 2

Bumps [Swatinem/rust-cache](https://github.com/swatinem/rust-cache) from 1 to 2.
- [Release notes](https://github.com/swatinem/rust-cache/releases)
- [Changelog](https://github.com/Swatinem/rust-cache/blob/master/CHANGELOG.md)
- [Commits](Swatinem/rust-cache@v1...v2)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/CI.yml

@@ -52,7 +52,7 @@ jobs:
         with:
           toolchain: ${{ matrix.rust }}
           components: rustfmt, clippy
-      - uses: Swatinem/rust-cache@v1
+      - uses: Swatinem/rust-cache@v2
       - name: Run rustfmt
         if: matrix.rust == 'stable' # Avoid differences between the versions
         run: cargo fmt --check