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] <[email protected]>

Author: dependabot[bot]

.github/workflows/docs.yml

@@ -90,7 +90,7 @@ jobs:
           cat requirements-full.txt
 
       - name: Setup caching for conda packages
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/conda_pkgs_dir
           key: conda-${{ runner.os }}-${{ env.PYTHON }}-${{ hashFiles('requirements-full.txt') }}

.github/workflows/test.yml

@@ -119,7 +119,7 @@ jobs:
           cat requirements-full.txt
 
       - name: Setup caching for conda packages
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ~/conda_pkgs_dir
           key: conda-${{ runner.os }}-${{ env.PYTHON }}-${{ hashFiles('requirements-full.txt') }}