Add legacy job to CI for Python 3.6 and 3.7 testing on ubuntu-22.04

Author: dvershinin

.github/workflows/pythonpackage.yml

@@ -3,12 +3,29 @@ name: Python tests
 on: [push, pull_request]
 
 jobs:
-  build:
+  legacy:
+    name: Test on Python ${{ matrix.python-version }}
+    runs-on: ubuntu-22.04
+    strategy:
+      matrix:
+        python-version: ['3.6', '3.7']
+    container:
+      image: python:${{ matrix.python-version }}
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install dependencies & test
+        run: |
+          pip install -r requirements.txt \
+                      -r requirements.dev.txt
+          flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+          pytest -v -n auto
+  modern:
+    name: Test on Python ${{ matrix.python-version }}
     runs-on: ubuntu-22.04
     strategy:
       max-parallel: 4
       matrix:
-        python-version: ['3.6', '3.7', '3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
     steps:
     - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}