Make `open311-update-reports' executable

Since FixaMinGata is still using bin/open311-update-reports, it would be nice if it could be executable.

Note that there are some other files in the bin directory that are also not executable:

* export-norwegian-contacts
* fetch-comments-24hs
* generate_council_location
* site-specific-install.sh
* oxfordshire/open311_services.pm (but being a module, I'm guessing that's correct)