heptapod-ci: remove push exception for named branches

The internal workings of Heptapod cause even fast-forward merges to look like
pushes to Gitlab. The only way to run a pipeline on topic-less named branches
is not through the web interface. I am probably the only person affected by
this, so it's not really a problem.

This was confirmed with Georges, the maintainer of Heptapod, though the only
way to be *actually* sure, is to merge this and see.

contrib/heptapod-ci.yml

@@ -3,12 +3,12 b''
 # `branch/stable`), but the hash hasn't changed. There is no reason to
 # re-run the CI in our case, since we haven't built up any specific automation.
 # Right now it's just wasted CI and developer time.
-# One can still run the pipeline manually via the web interface or a push,
+# One can still run the pipeline manually via the web interface,
 # like in the case of releases, to make *extra* sure that the actual branch
 # has succeeded.
 workflow:
   rules:
-    - if: $CI_COMMIT_BRANCH =~ /^branch\/.*/ && $CI_PIPELINE_SOURCE != "web" && $CI_PIPELINE_SOURCE != "push"
+    - if: $CI_COMMIT_BRANCH =~ /^branch\/.*/ && $CI_PIPELINE_SOURCE != "web"
       when: never
     - if: $CI_PIPELINE_SOURCE == "merge_request_event"
     - if: $CI_COMMIT_BRANCH && $CI_OPEN_MERGE_REQUESTS