`rsvp move` doesn't handle percent-encoded slashes in URLs

[zachallaun]

Originally opened by @strugee wtfcarlos/RSVPBot#75:

rsvp move https://recurse.zulipchat.com/#narrow/stream/RSVPs/topic/Security.20club.3A.20HTTPS.20pt.2E.201.2Foperational.20security resulted in the event being moved to Security club: HTTPS pt. 1 instead of Security club: HTTPS pt. 1/operational security