CI: Checkout Git submodules

Update the CI to work with the new vendor/cdict submodule.
The checkout action is upgraded to v6.

Author: Julow

.github/workflows/make-apk.yml

@@ -10,7 +10,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout repo
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
+      with:
+        submodules: true
     - name: Restore debug keystore from GitHub Secrets
       run: |
         # Check if exist and use the secret named DEBUG_KEYSTORE