Moving a folder using move(to:) creates an invalid path

[clayellis]

1. Create folder A
2. Create folder B inside A
3. Create folder C inside B

   .
   ├─ A
   └─ B
      └─ C

4. Move B to same level as A

   .
   ├─ A
   ├─ B
   └─ C

5. Try getting subfolder C with b.subfolder(named: "C") - error

Invalid path given: /Users/clay/.filesTest/BC/

This is because move(to:) removes the trailing / from the moved item's path. I'm submitting a PR that fixes this along with a test to catch this in the future.