Bump actions/cache from 2 to 3

Bumps [actions/cache](https://github.com/actions/cache) from 2 to 3.
- [Release notes](https://github.com/actions/cache/releases)
- [Commits](actions/cache@v2...v3)

---
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/ci.yaml

@@ -42,7 +42,7 @@ jobs:
 
       - name: Cache tox environments
         id: cache-tox
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: .tox
           # requirements/*.txt and pyproject.toml have versioning info
@@ -84,7 +84,7 @@ jobs:
         uses: docker/setup-buildx-action@v1
 
       - name: Cache Docker layers
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: /tmp/.buildx-cache
           key: ${{ runner.os }}-buildx-${{ github.sha }}