Bump actions/cache from 5 to 6

Bumps [actions/cache](https://github.com/actions/cache) from 5 to 6.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v5...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>

Author: dependabot[bot]

.github/workflows/benchmark.yml

@@ -17,7 +17,7 @@ jobs:
           elixir-version: "1.20"
           otp-version: "29"
       - name: Cache deps and build for mix
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: |
             bench/deps

.github/workflows/build-test.yml

@@ -35,7 +35,7 @@ jobs:
           otp-version: ${{ matrix.otp }}
           elixir-version: ${{ matrix.elixir }}
       - name: Cache deps and build for mix
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         id: cache-mix
         with:
           path: |
@@ -46,7 +46,7 @@ jobs:
             ${{ matrix.os }}-mix-${{ env.MIX_ENV }}-${{ matrix.elixir }}-${{ matrix.otp }}-
             ${{ matrix.os }}-mix-${{ env.MIX_ENV }}-
       - name: Cache plt for dialyzer
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         id: cache-plt
         with:
           path: _build/${{ env.MIX_ENV }}/dialyxir_*
@@ -87,7 +87,7 @@ jobs:
           otp-version: ${{ matrix.otp }}
           elixir-version: ${{ matrix.elixir }}
       - name: Cache deps and build for mix
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         id: cache-mix
         with:
           path: |