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](actions/setup-python@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>

.github/workflows/pex-build-upload.yml

@@ -19,7 +19,7 @@ jobs:
         with:
           submodules: recursive
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: 3.x
       - name: Set up Go

.github/workflows/python-black.yml

@@ -10,5 +10,5 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-python@v2
+      - uses: actions/setup-python@v4
       - uses: psf/black@main

.github/workflows/python-pip-publish.yml

@@ -13,7 +13,7 @@ jobs:
         with:
           submodules: recursive
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: 3.x
       - name: Install dependencies

.github/workflows/test.yml

@@ -28,7 +28,7 @@ jobs:
         with:
           submodules: recursive
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install testing dependencies