⬆ Bump actions/setup-python from 2 to 4 (#5129)

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>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/build-docs.yml

@@ -15,7 +15,7 @@ jobs:
         run: echo "$GITHUB_CONTEXT"
       - uses: actions/checkout@v2
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: "3.7"
       - uses: actions/cache@v2

.github/workflows/publish.yml

@@ -15,7 +15,7 @@ jobs:
         run: echo "$GITHUB_CONTEXT"
       - uses: actions/checkout@v2
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: "3.6"
       - uses: actions/cache@v2

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
       - uses: actions/cache@v2