ci(lfs): attempt at cache lfs to reduce bandwidth

See issue #108 and actions/checkout#165 (comment)

.github/workflows/tests.yaml

@@ -23,8 +23,21 @@ jobs:
       COVERAGE_FILE: ${{ github.workspace }}/.coverage.${{ matrix.python-version }}-${{ matrix.tests }}
     steps:
       - uses: actions/checkout@v2
+      - name: Create LFS file list
+        run: |
+          git lfs ls-files -l | cut -d' ' -f1 | sort > .lfs-assets-id
+      - name: Restore LFS cache
+        uses: actions/cache@v2
+        id: lfs-cache
         with:
-          lfs: true
+          path: .git/lfs
+          # The cache of lfs should be the same on all jobs. Not sure
+          # what happens when an updated has occured and every job tries
+          # to upload a new versions.
+          # key: ${{ runner.os }}-lfs-${{ hashFiles('.lfs-assets-id') }}-v1
+          key: lfs-${{ hashFiles('.lfs-assets-id') }}-v1
+      - name: Git LFS Pull
+        run: git lfs pull
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v2
         with: