Bump actions/cache from 3 to 4

Bumps [actions/cache](https://github.com/actions/cache) from 3 to 4.
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v3...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/tests.yml

@@ -104,7 +104,7 @@ jobs:
 
       - name: Restore dependencies and Wikipedia cache(Ubuntu)
         if: matrix.os == 'ubuntu-latest'
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             ~/.config/calibre/plugins/worddumb-libs-py*
@@ -113,7 +113,7 @@ jobs:
 
       - name: Restore dependencies and Wikipedia cache(macOS)
         if: matrix.os == 'macos-latest'
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             ~/Library/Preferences/calibre/plugins/worddumb-libs-py*
@@ -122,7 +122,7 @@ jobs:
 
       - name: Restore dependencies and Wikipedia cache(Windows)
         if: matrix.os == 'windows-latest'
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: |
             ~/AppData/Roaming/calibre/plugins/worddumb-libs-py*