build(deps): 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/tf-checks.yml

@@ -138,7 +138,7 @@ jobs:
           fi
 
       - name: ♻️ Cache Terraform plugins
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: ${{ env.TF_PLUGIN_CACHE_DIR }}
           key: terraform-${{ runner.os }}-${{ hashFiles('**/.terraform.lock.hcl') }}

.github/workflows/tf-lint.yml

@@ -17,7 +17,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: 💾 Cache plugin dir
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: ~/.tflint.d/plugins
           key: ubuntu-latest-tflint-${{ hashFiles('.tflint.hcl') }}