ci: use cache@v6

.github/workflows/testing.yml

@@ -28,19 +28,19 @@ jobs:
         python-version: ${{ matrix.python-version }}
         cache: pip
 
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install .[ai-features,dev]
+
     - name: Cache APT packages
-      uses: actions/cache@v4
+      uses: actions/cache@v6
       with:
         path: /var/cache/apt/archives
         key: ${{ runner.os }}-apt-${{ hashFiles('**/apt-packages.txt') }}
         restore-keys: |
           ${{ runner.os }}-apt-
 
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip
-        python -m pip install .[ai-features,dev]
-
     - name: Install sharkd (marker replay engine)
       run: |
         sudo apt-get update