Add deb to CI

.gitlab-ci.yml

-image: python:3.7
-
 stages:
   - quality-assurance
-
-before_script:
-  - pip install tox
+  - build
 
 linters:
+  image: python:3.7
   stage: quality-assurance
-  script: tox -e linters
+  before_script:
+    - pip install tox
+  script:
+    - tox -e linters
 
   # Be nice to new contributors, but please use `tox` before commit
   allow_failure: true
+
+build-deb:
+  image: debian:buster
+  stage: build
+  script:
+    - apt-get update && apt-get -y --no-install-recommends install debmake dh-python debhelper python3-all
+    - dpkg-buildpackage
+    - mkdir build && cp ../*.deb build/
+  artifacts:
+    paths:
+      - build/*.deb