chore: bump actions/setup-python from 2 to 4 (#752)

* chore: bump actions/setup-python from 2 to 4

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 2 to 4.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](https://github.com/actions/setup-python/compare/v2...v4)

---
updated-dependencies:
- dependency-name: actions/setup-python
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

* Apply suggestions from code review

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Henry Schreiner <henry.fredrick.schreiner@cern.ch>

.github/workflows/build.yml

@@ -17,7 +17,9 @@ jobs:
         with:
           submodules: true
 
-      - uses: actions/setup-python@v2
+      - uses: actions/setup-python@v4
+        with:
+          python-version: "3.x"
 
       - name: Prepare CMake config
         run: cmake -S . -B build -DCLI11_SINGLE_FILE=ON