If you don't have https support installed this line will be a problem (maybe you do, as it's not the problem you're posting about):

my $URL= get("https://www.events.utoronto.ca/iCal.php?ical=1&campus=0&sponsor%5­B%5D=&audience%5B%5D=&category%5B%5D=");

You should be checking the return value from LWP::Simple::get(). If it's undef, you didn't get a successful response. In this case you can solve the this part of the problem simply by switching to http:// instead of https://, or by installing LWP::Protocol::https. But still get in the habit of checking for undef after using LWP::Simple::get.

You should be able to enable https support in LWP::Simple by following the advice in the README for LWP:

If you want to access sites using the https protocol, then you need to install the LWP::Protocol::https module from CPAN.

Once this is done, LWP::Simple is able to fetch the https request. (And maybe you've done this already).