build(deps): bump actions/cache from 2 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 2 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](https://github.com/actions/cache/compare/v2...v4)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/pages.yml

@@ -41,7 +41,7 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version: 3.x
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           key: ${{ github.ref }}
           path: .cache

.github/workflows/verify-pages.yml

@@ -28,7 +28,7 @@ jobs:
       - uses: actions/setup-python@v5
         with:
           python-version: 3.x
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         with:
           key: ${{ github.ref }}
           path: .cache