chore(deps): bump the actions group with 2 updates

Bumps the actions group with 2 updates: [actions/checkout](https://github.com/actions/checkout) and [actions/cache](https://github.com/actions/cache).


Updates `actions/checkout` from 4 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Commits](actions/checkout@v4...v6)

Updates `actions/cache` from 5.0.3 to 5.0.4
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@cdf6c1f...6682284)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: actions/cache
  dependency-version: 5.0.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
...

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

Author: dependabot[bot]

.github/workflows/boj-build.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Trigger BoJ Server (Casket/ssg-mcp)
         run: |
           # Send a secure trigger to boj-server to build this repository

.github/workflows/casket-pages.yml

@@ -35,7 +35,7 @@ jobs:
           cabal-version: '3.10'
 
       - name: Cache Cabal
-        uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v4
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v4
         with:
           path: |
             ~/.cabal/packages