update action file

Author: DomAmato

.github/workflows/testlint.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.7]
+        python-version: [3.9]
 
     steps:
     - uses: actions/checkout@v2
@@ -20,7 +20,8 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install -r requirements-dev.txt
+        pip install -r requirements-test.txt
+        pip install -r requirements.txt
     
     - name: Lint with flake8
       run: |