try to fix build

.github/workflows/python-package.yml

@@ -1,38 +1,39 b''
 # This workflow will install Python dependencies, run tests and lint with a variety of Python versions
 # For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions
 
 name: Python package
 
 on:
   push:
     branches: [ master ]
   pull_request:
     branches: [ master ]
 
 jobs:
   build:
 
     runs-on: ubuntu-latest
     strategy:
       matrix:
         python-version: [3.8]
 
     steps:
     - uses: actions/checkout@v2
+      with: 
+        fetch-depth: 0
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
         pip install darker
     - name: Lint with darker
       run: |
-        git fetch
         darker -r 60625f241f298b5039cb2debc365db38aa7bb522 --check --diff . || (
         echo "Changes need auto-formatting. Run:"
         echo "    darker -r 60625f241f298b5039cb2debc365db38aa7bb522"
         echo "then commit and push changes to fix."
         exit 1
         )