build(deps): bump actions/cache from 3 to 4 (#8)

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

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -57,7 +57,7 @@ jobs:
       - name: Check cached version info to see if current commit has been built before
         id: restore-cache-macvim-commit
         if: ${{ github.event_name != 'workflow_dispatch' }}
-        uses: actions/cache/restore@v3
+        uses: actions/cache/restore@v4
         with:
           path: ${{ github.workspace }}/macvim-built-commit.txt
           key: macvim-built-commit-${{ steps.setup-env-vars.outputs.docs_commit}}-${{ steps.setup-env-vars.outputs.macvim_commit }}
@@ -127,7 +127,7 @@ jobs:
 
       - name: Update cache with commit version info
         id: save-cache-macvim-commit
-        uses: actions/cache/save@v3
+        uses: actions/cache/save@v4
         if: ${{ needs.build.outputs.macvim_commit_cache_hit != 'true' && github.event_name != 'workflow_dispatch' }}
         with:
           path: ${{ github.workspace }}/macvim-built-commit.txt