ntfy: Avoid duplicate '//'
If the URL ends with a slash like
[Ntfy]
Url=https://ntfy.example.com/
we'd end up with two slashes in the URL
https://ntfy.example.com//upk…
which then confuses ntfy.
If the URL ends with a slash like
[Ntfy]
Url=https://ntfy.example.com/
we'd end up with two slashes in the URL
https://ntfy.example.com//upk…
which then confuses ntfy.