Remove authors from gitchangelog output

Given our workflow, this could easily lead to misattribution. It's also
not an actionable information and it can be found in the MR / git log
instead.

(cherry picked from commit a8258d1c53)

contrib/gitchangelog/gitchangelog.py

@@ -1508,7 +1508,6 @@ def rest_py(data, opts={}):
 
     def render_commit(commit, opts=opts):
         subject = commit["subject"]
-        subject += " [%s]" % (", ".join(commit["authors"]),)
 
         entry = indent("\n".join(textwrap.wrap(subject)), first="- ").strip() + "\n"