exec_on_new seems to be ignored

[eswenson1]

I have:

[hooks]
# Trigger terminal-notifier for every new feed item
exec_on_new = "terminal-notifier -title 'New Feed Item' -message '{{title}}' -subtitle '{{feed_name}}' -open '{{url}}'"

in my feedr/config.toml file. I have background refresh enabled and set to 30 seconds (for testing). While the display flashes suggesting that it is updating, terminal-notifier is never invoked -- at least I don't ever get any notifications. If I invoke that command manually from the shell, I do see the notifications pop up.

I'm on macOS. I'm using the main branch.