add authors check in CI

.gitlab-ci.yml

 image: quantumtinkerer/research
+
 test:
   script:
     - pip install -r test-requirements.txt
@@ -7,3 +8,9 @@ test:
   artifacts:
     paths:
       - htmlcov
+
+authors check:
+  script:
+    - MISSING_AUTHORS=$(git shortlog -s HEAD | sed -e "s/^[0-9\t ]*//"| xargs -i sh -c 'grep -q "{}" AUTHORS.md || echo "{} missing from authors"')
+    - if [ ! -z "$MISSING_AUTHORS" ]; then { echo $MISSING_AUTHORS; exit 1; }; fi
+  allow_failure: true