CI: Updating build instructions

Signed-off-by: Thomas Karl Pietrowski <thopiekar@gmail.com> (github: thopiekar)

.gitlab-ci.yml

 stages:
   - build
 
+variables:
+  GIT_SUBMODULE_STRATEGY: recursive
+
 all:
   stage: build
   tags:
     - os:ubuntu,
     - package:python3
     - type:shell
-  before_script:
-    - git submodule sync --recursive
-    - git submodule update --init --recursive
   script:
     - curl https://thopiekar.eu:5443/cura-plugins/CuraPluginOven/raw/deployment/cpo.py?inline=false --output cpo.py
     - python3 ./cpo.py --create=package6 --source=./
+    - python3 ./cpo.py --create=plugin4 --source=./
     - python3 ./cpo.py --create=source --source=./
-    - python3 ./cpo.py --create=plugin5 --source=./
   only:
     - triggers
     - branches