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](https://github.com/actions/cache/compare/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>

.github/workflows/buildtester.yml

@@ -127,7 +127,7 @@ jobs:
         shell: bash
   
       - name: Pass to Windows 💸
-        uses: actions/cache/save@v3
+        uses: actions/cache/save@v4
         with:
           path: MagiskOnWSA/output
           key: ${{ steps.wsa.outputs.artifact }}-${{ steps.date.outputs.date }}
@@ -147,7 +147,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Download built artifact ⌛
-        uses: actions/cache/restore@v3
+        uses: actions/cache/restore@v4
         with:
           path: output
           key: ${{ needs.build.outputs.artifact }}-${{ needs.build.outputs.date }}