pipeline: upgrade checkout action in attempt to fix git-lfs checkout

.github/workflows/python.yml

@@ -42,9 +42,9 @@ jobs:
         - 3.9
       fail-fast: false
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
       with:
-        lfs: '' # tests/resources/
+        lfs: true # tests/resources/
     - uses: actions/setup-python@v1
       with:
         python-version: ${{ matrix.python-version }}