chore: 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/build.yml

@@ -25,7 +25,7 @@ jobs:
       run: |
         python -m poetry config virtualenvs.in-project true
     - name: Cache the virtualenv
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: ./.venv
         key: ${{ runner.os }}-venv-${{ hashFiles('**/poetry.lock') }}

.github/workflows/docs.yml

@@ -26,7 +26,7 @@ jobs:
         run: |
           python -m poetry config virtualenvs.in-project true
       - name: Cache the virtualenv
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ./.venv
           key: ${{ runner.os }}-venv-${{ hashFiles('**/poetry.lock') }}