gha: remove old pyver and bump actions version

.github/workflows/tests.yml

@@ -22,16 +22,13 @@ jobs:
         os:
           - ubuntu-20.04
         python-version:
-          - 3.5
           - 3.6
-        requirements:
-          - requirements.txt
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
 
@@ -45,8 +42,7 @@ jobs:
     - name: Install Python ${{ matrix.python-version }} dependencies
       run: |
         pip install --upgrade pip
-        python -m pip install -r ${{ matrix.requirements }}
+        python -m pip install -r requirements.txt
 
     - name: Run tests
       run: python tests/test.py default
-