Important note: you should NEVER do this to trailing slashes that exist in the path itself!
https://simonwillison.net/tags and https://simonwillison.net/tags/ are not technically the same URL
But... https://simonwillison.net/ and https://simonwillison.net ARE the same
And if you've decided not to display the https:// protocol, I think it looks prettier if you don't show the trailing slash either
(This is possibly the least important aesthetic preference anyone has ever expressed)