Revert "CI: fix submodule recursive cloning"

This reverts commit 3725f92f.

.gitlab-ci.yml

@@ -8,7 +8,6 @@ variables:
 test-job:
   stage: test
   script:
-    - git submodule update --init --recursive
     - python3 -m venv .venv             # Create Python virtual environment
     - source .venv/bin/activate         # Activate Python virtual environment
     - pip3 install -r requirements.txt  # Install Python dependencies