Drop support for Python 3.5

.github/workflows/tests.yml

@@ -38,7 +38,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [3.5, 3.6, 3.7, 3.8]
+        python-version: [3.6, 3.7, 3.8]
 
     steps:
     - uses: actions/checkout@v2
@@ -64,7 +64,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install -r requirements.txt
-        cat requirements-dev.txt | xargs -n 1 pip install
+        pip install -r requirements-dev.txt
 
     - name: Run tests
       run: |