github workflow: remove unsupported yaml anchors

> The workflow is not valid. .github/workflows/python.yml: Anchors are not currently supported. Remove the anchor 'setup_python'
https://github.com/fphammerle/ical2vdir/actions/runs/139568843

This reverts commit 74750675cbb453fe225bbd382a5057cfdbdd129c.

.github/workflows/python.yml

@@ -19,14 +19,11 @@ jobs:
         - 3.8
     steps:
     - uses: actions/checkout@v1
-    - &setup_python
-      uses: actions/setup-python@v1
+    - uses: actions/setup-python@v1
       with:
         python-version: ${{ matrix.python-version }}
-    - &pip_install_pipenv
-      run: pip install --upgrade pipenv>=2018.10.9
-    - &pipenv_install
-      run: pipenv install --python "$PYTHON_VERSION" --deploy --dev
+    - run: pip install --upgrade pipenv>=2018.10.9
+    - run: pipenv install --python "$PYTHON_VERSION" --deploy --dev
       env:
         PYTHON_VERSION: ${{ matrix.python-version }}
     - run: pipenv graph
@@ -42,9 +39,13 @@ jobs:
         - 3.8
     steps:
     - uses: actions/checkout@v1
-    - *setup_python
-    - *pip_install_pipenv
-    - *pipenv_install
+    - uses: actions/setup-python@v1
+      with:
+        python-version: ${{ matrix.python-version }}
+    - run: pip install --upgrade pipenv>=2018.10.9
+    - run: pipenv install --python "$PYTHON_VERSION" --deploy --dev
+      env:
+        PYTHON_VERSION: ${{ matrix.python-version }}
     - run: pipenv graph
     - run: pipenv run pytest --cov=ical2vdir --cov-report=term-missing --cov-fail-under=100
     - run: pipenv run pylint --load-plugins=pylint_import_requirements ical2vdir