Bump actions/cache from 2 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 2 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v2...v4)

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

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

Author: dependabot[bot]

.github/workflows/main.yml

@@ -69,7 +69,7 @@ jobs:
         submodules: true
 
     - name: Restore cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: ~/cache
         key: ${{ runner.os }}-${{ matrix.target }}