Move pyupgrade check to main workflow

Add `pyupgrade` to test dependencies.

.github/workflows/lint_python.yml

@@ -8,8 +8,6 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions/setup-python@v2
       - run: pip install --upgrade pip wheel
-      - run: pip install
-                 pyupgrade safety
+      - run: pip install safety
       - run: pip install --editable .
-      - run: shopt -s globstar && pyupgrade --py36-plus **/*.py
       - run: safety check

.github/workflows/python-package.yml

@@ -87,3 +87,14 @@ jobs:
         run: bandit --recursive --skip B101 ./src/darker/tests
       - name: Check English spelling in the code base using codespell
         run: codespell
+      - name: Ensure modern Python style using pyupgrade
+        # This script is written in a Linux / macos / windows portable way
+        run: |
+          python -c "
+          from pyupgrade._main import main
+          from glob import glob
+          files = glob('**/*.py', recursive=True)
+          main(files + ['--py36-plus'])
+          "
+      - name: Check dependencies for known security vulterabilities using Safety
+        run: safety check

constraints-oldest.txt

@@ -14,6 +14,7 @@ pytest==6.1.0
 pytest-flake8==1.0.6
 pytest-isort==1.1.0
 pytest-kwparametrize==0.0.3
+pyupgrade==2.31.0
 regex==2021.4.4
 toml==0.10.0
 types-toml==0.10.4

setup.cfg

@@ -58,14 +58,15 @@ test =
     flake8-bugbear>=22.1.11
     flake8-comprehensions>=3.7.0
     mypy>=0.931
+    pygments
     pylint
     pytest>=6.1.0
     pytest-darker
     pytest-flake8>=1.0.6
     pytest-isort>=1.1.0
     pytest-kwparametrize>=0.0.3
     pytest-mypy
-    pygments
+    pyupgrade>=2.31.0
     regex>=2021.4.4
     types-dataclasses ; python_version < "3.7"
     types-toml>=0.10.4