Update package_linter.yml

.github/workflows/package_linter.yml

@@ -15,6 +15,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+      
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.9'
+      
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install toml
 
       - name: 'Clone YunoHost apps package linter'
         run: |