Add older Python versions (#867)

Author: thom-at-redhat

.github/workflows/pull_request.yml

@@ -104,10 +104,11 @@ jobs:
   receptorctl:
     name: receptorctl (Python ${{ matrix.python-version }})
     needs: receptor
-    runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11"]
+        os-version: ["ubuntu-22.04"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11"]
+    runs-on: "${{ matrix.os-version }}"
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -126,7 +127,10 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v4
         with:
-          python-version: '${{ matrix.python-version }}'
+          python-version: "${{ matrix.python-version }}"
+
+      - name: Upgrade pip
+        run: pip install --upgrade pip
 
       - name: Install tox
         run: pip install tox