ci: more optimization, lets not install pytest etc because it should already be in the image

.gitlab/ci/test.gitlab-ci.yml

@@ -1,6 +1,5 @@
 .install_debs: &install_debs
     - DEBIAN_FRONTEND=noninteractive SUDO_FORCE_REMOVE=yes apt --assume-yes -o Dpkg::Options::="--force-confold" --allow-downgrades install ${CI_PROJECT_DIR}/*.deb
-    - pip3 install -U mock pip pytest pytest-cov pytest-mock pytest-sugar requests-mock "packaging<22"
 
 .test-stage:
   stage: test