CI: Run ruff as a style check

.github/workflows/contrib.yml

@@ -22,31 +22,12 @@ permissions:
   contents: read
 
 jobs:
-  stable:
-    runs-on: ${{ matrix.os }}
-    strategy:
-      matrix:
-        os: ['ubuntu-latest']
-        python-version: [3]
-
+  style:
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
-        with:
-          python-version: ${{ matrix.python-version }}
-      - name: Display Python version
-        run: python -c "import sys; print(sys.version)"
-      - name: Install black/isort
-        run: python -m pip install black isort[colors]
-      - name: Check fMRIPrep
-        run: |
-          python -m black --diff --color --check fmriprep
-          python -m isort --diff --color --check fmriprep
-      - name: Check wrapper
-        run: |
-          python -m black --diff --color --check wrapper
-          python -m isort --diff --color --check wrapper
+      - run: pipx run ruff fmriprep
+      - run: pipx run ruff format --diff fmriprep
 
   codespell:
     name: Check for spelling errors