Set verify_SSL=>1 for default HTTP::Tiny user agent

[stigtsp]

HTTP::Tiny doesn't verify TLS/SSL certificates by default. This PR sets that flag for the default user agent to make sure we connect to legitimate API endpoints.

Example: MetaCPAN::Client will perform a request (that returns 404 Not Found) against https://wrong.host.badssl.com:

$ perl -Ilib -MMetaCPAN::Client -E 'my $m = MetaCPAN::Client->new(domain=>"https://wrong.host.badssl.com");say $m->release("MetaCPAN-Client")->name;'
Failed to fetch 'https://wrong.host.badssl.com/release/MetaCPAN-Client': Not Found at lib/MetaCPAN/Client.pm line 288.