chore(deps): update actions/cache action to v5 (#18)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/cache](https://github.com/actions/cache) | action | major | `v4` -> `v5` |

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### Release Notes

<details>
<summary>actions/cache (actions/cache)</summary>

### [`v5`](https://github.com/actions/cache/compare/v4...v5)

[Compare Source](https://github.com/actions/cache/compare/v4...v5)

</details>

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### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

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This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
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Reviewed-on: t.behrendt/trivy-actions#18
Reviewed-by: t.behrendt <t.behrendt@noreply.localhost>
Co-authored-by: Renovate Bot <renovate@t00n.de>
Co-committed-by: Renovate Bot <renovate@t00n.de>

setup-db/action.yaml

@@ -24,7 +24,7 @@ runs:
       run: |
         echo "current-date=$(date +%Y-%m-%d)" >> $GITHUB_OUTPUT
     - id: restore-db
-      uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
+      uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5
       with:
         path: ${{ inputs.cache-dir }}
         key: trivy-db-${{ steps.current-date.outputs.current-date }}

setup-trivy/action.yaml

@@ -40,7 +40,7 @@ runs:
         echo "VERSION=$VERSION" >> $GITHUB_OUTPUT
     - name: Cache Trivy binary
       id: cache-trivy
-      uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
+      uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5
       with:
         path: /usr/local/bin/trivy
         key: trivy-${{ steps.version.outputs.version }}-${{ steps.arch.outputs.arch }}