Remove commented gitlab-code-quality dep and use in CI

.gitlab-ci.yml

@@ -118,7 +118,6 @@ pytest:
   script:
     - pytest
     - mv .coverage .coverage.main
-#    --gitlab-code-quality-report=pytest-warnings.json # can restore when it installs ok
   artifacts:
     when: always
     paths:

pyproject.toml

@@ -37,7 +37,6 @@ dependencies = [
 dev = [
   "ruff~=0.15.1",
   "mypy[reports]",
-#  "pytest-gitlab-code-quality", # pytest version constraint clashes with labthings
   "pytest",
   "pytest-cov",
   "pytest-mock==3.14",