(maint) Update GRM template

Now that we are switching to a newer version of GitReleaseManager, we
need to switch the template variable being used.  This changed from
number to public_number.

Author: gep13

.templates/default/issue-note.sbn

@@ -1,6 +1,6 @@
 {{
     if issue_label == "Bug" || issue_label == "Bug Fix" || issue_label == "Bug Fixes"
-}}- Fix - {{ issue.title }} - see [#{{ issue.number }}]({{ issue.html_url }}).
+}}- Fix - {{ issue.title }} - see [#{{ issue.public_number }}]({{ issue.html_url }}).
 {{  else
-}}- {{ issue.title }} - see [#{{ issue.number }}]({{ issue.html_url }}).
+}}- {{ issue.title }} - see [#{{ issue.public_number }}]({{ issue.html_url }}).
 {{  end -}}