test_astobj2: Fix warning for missing trailing slash in category

This patch adds a trailing slash to the category for this test.
No more warning.

Tested-by: George Joseph

Review: https://reviewboard.asterisk.org/r/4295/
........

Merged revisions 430059 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@430060 65c4cc65-6c06-0410-ace0-fbb531ad65f3