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)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [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/build_docs.yml

@@ -17,7 +17,7 @@ jobs:
       with:
         python-version: 3.9
 
-    - uses: actions/cache@v2
+    - uses: actions/cache@v3
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}

.github/workflows/run_tests.yml

@@ -21,7 +21,7 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
 
-    - uses: actions/cache@v2
+    - uses: actions/cache@v3
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-pip-${{ hashFiles('**/setup.py') }}