build(deps): bump actions/setup-python from 2.3.2 to 3

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 2.3.2 to 3.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](https://github.com/actions/setup-python/compare/v2.3.2...v3)

---
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/python.yml

@@ -18,7 +18,7 @@ jobs:
         python-verison: ['3.9']
     steps:
     - uses: actions/checkout@v2.4.0
-    - uses: actions/setup-python@v2.3.2
+    - uses: actions/setup-python@v3
       with:
         python-version: ${{ matrix.python-version }}
         # did not reduce runtime of `pipenv install` (still approx. 1 min)
@@ -41,7 +41,7 @@ jobs:
       fail-fast: false
     steps:
     - uses: actions/checkout@v2.4.0
-    - uses: actions/setup-python@v2.3.2
+    - uses: actions/setup-python@v3
       with:
         python-version: ${{ matrix.python-version }}
         # did not reduce runtime of `pipenv install` (still approx. 1 min)
@@ -76,7 +76,7 @@ jobs:
         python-verison: ['3.9']
     steps:
     - uses: actions/checkout@v2.4.0
-    - uses: actions/setup-python@v2.3.2
+    - uses: actions/setup-python@v3
       with:
         python-version: ${{ matrix.python-version }}
     - run: pip install --upgrade pipenv==2020.8.13