gitlab-ci: only run issuebot on 'branches'

Hopefully, it will still reliably trigger but only run once per push.
The wheel switch is to get rid of the bdist_wheel error messages.

.gitlab-ci.yml

@@ -196,6 +196,8 @@ fdroid build:
 pages:
   image: registry.gitlab.com/fdroid/ci-images-client:latest
   only:
+    refs:
+      - branches
     variables:
       - $FROM_CI_MERGE_REQUEST_IID
   artifacts:
@@ -240,7 +242,8 @@ pages:
         | tar -xz --strip-components=1
     - pyvenv --system-site-packages --clear issuebot-env
     - . issuebot-env/bin/activate
-    - pip3 install python-gitlab wheel pygithub
+    - pip3 install wheel # get rid of the bdist_wheel error messages
+    - pip3 install python-gitlab pygithub
     - ./issuebot.py
 
     # git_stats used to run here, redirect to new location