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>

Author: dependabot[bot]

.github/workflows/ci-tests.yml

@@ -62,7 +62,7 @@ jobs:
 
       - name: MyPy cache
         if: ${{ matrix.step == 'mypy' }}
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: .mypy_cache/${{ env.py-semver }}
           key: mypy-${{ env.py-semver }}