fix python36 pip bug 2

Author: antoinedemathelin

.github/workflows/run-test.yml

@@ -18,6 +18,8 @@ jobs:
         exclude:
           - os: windows-latest
             python-version: 3.9
+          - os: ubuntu-latest
+            python-version: 3.6
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2
@@ -27,7 +29,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
-        python -m pip install --upgrade --no-cache-dir pip
+        python -m pip install --upgrade pip
         pip install pytest pytest-cov codecov
         pip install -r requirements.txt
     - name: Install adapt