Remove options from isort that aren't part of 5.x

`-y` and `-rc` are now default behaviour and no longer exist.

`dont-skip` is no longer required

https://timothycrosley.github.io/isort/CHANGELOG/#500-penny-july-4-2020

scripts-dev/lint.sh

@@ -15,7 +15,7 @@ else
 fi
 
 echo "Linting these locations: $files"
-isort -y -rc $files
+isort $files
 python3 -m black $files
 ./scripts-dev/config-lint.sh
 flake8 $files