chore: bump actions/cache from 4 to 6

Bumps [actions/cache](https://github.com/actions/cache) from 4 to 6.
- [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/v4...v6)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/android.yml

@@ -46,7 +46,7 @@ jobs:
 
       - name: Cache ktlint
         id: cache-ktlint
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: ~/.local/bin/ktlint
           key: ktlint-1.2.1
@@ -261,7 +261,7 @@ jobs:
       # Cache the AVD to avoid downloading/recreating it from scratch every time
       - name: AVD Cache
         id: avd-cache
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.android/avd/*