Added SonarQube to the pipeline.

.gitlab-ci.yml

@@ -2,7+2,7 @@
 stages:
   - tox
   - documentation
 
 include:
   - docs/.gitlab-ci.yml
 
@@ -46,7+46,7 @@
   artifacts:
     paths:
       - htmlcov
+
+  sonarqube-analysis:
+    image: sonarsource/sonar-scanner-cli
+    script:
+      - sonar-scanner
+    only:
+      - develop