[ci] Run latest version of Python avaialble on the system

.github/workflows/ci.yml

@@ -31,16 +31,16 @@ jobs:
           key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
           restore-keys: ${{ runner.os }}-yarn-
 
-      - name: Set up Python 3.10
+      - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.10"
           cache: "pip"
           cache-dependency-path: "**/requirements*.txt"
 
       - name: Installing dependencies
         run: |
           yarn install
+          python --version
           pip install -r requirements-qa.txt
 
       - name: QA checks
@@ -75,10 +75,9 @@ jobs:
       - name: Tests
         run: yarn coverage
 
-      - name: Set up Python 3.10
+      - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.10"
           cache: "pip"
           cache-dependency-path: "**/requirements*.txt"
 
@@ -88,12 +87,13 @@ jobs:
           cd openwisp-radius
           echo "OpenWISP RADIUS commit: $(git rev-parse HEAD)"
           echo "OW_RADIUS_VERSION=$(git rev-parse HEAD)" >> $GITHUB_ENV
+          python --version
 
       - name: Cache python environment
         uses: actions/cache@v4
         with:
-          path: ${{ env.pythonLocation }}
-          key: ${{ env.pythonLocation }}-${{ env.OW_RADIUS_VERSION }}
+          path: ~/.cache/pip
+          key: ${{ env.OW_RADIUS_VERSION }}
 
       - name: Installing OpenWISP Radius
         run: |