Increase duration timeout task manager

Sometimes, Jenkins or Travis is slow, and can't hit that 1 second timeout. This increases to 5 seconds to account for local slowness.

## Verification
 - [x] Run `rspec --format=d spec/lib/msf/core/task_manager_spec.rb`
 - [x] See success on, 'should handle task timeouts'

If you can figure out how to simulate a slow machine, feel free to post here. I suppose you can do this on a VM with restricted resources, like low RAM, one proc, etc.