Bump actions/cache from 3 to 4 (#125)

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>

.github/workflows/ci.yml

@@ -60,7 +60,7 @@ jobs:
           elixir-version: ${{ matrix.elixir }}
 
       - name: Cache mix deps
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         id: cache-deps
         with:
           path: |
@@ -107,7 +107,7 @@ jobs:
           otp-version: ${{ matrix.otp }}
 
       - name: Cache mix deps
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         id: cache-deps
         with:
           path: |