Fixing typo in the crontab.example file

I'm assuming here that the intention was to set the purge_pending_users.srfsh
job to run at 2:30 a.m., but it was set to run at 30:02 - obviously an invalid
time.

Signed-off-by: Chris Sharp <csharp@georgialibraries.org>
Signed-off-by: Dan Scott <dscott@laurentian.ca>