Bump actions/cache from 3 to 4 (#36)

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

Author: dependabot[bot]

.github/workflows/main.yml

@@ -22,15 +22,15 @@ jobs:
         run: |
           echo "date=$(/bin/date -u "+%Y%m%d")" >> $GITHUB_OUTPUT
       - name: Cache ccache
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             ~/.ccache
           key: ${{ runner.os }}-ccache-${{ steps.get-date.outputs.date }}
           restore-keys: |
             ${{ runner.os }}-ccache-
       - name: Cache pip
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             ~/.cache/pip