As of BBEdit 13.1, the HTML Tidy built-ins are back and you should use those instead. This gist is so old it refers to "OS X", c’mon!
If for some reason you are using this, note @ryanfrancesconi’s comment about the correct place to put the file when using sandboxed versions of BBEdit.
Thanks, this is super handy!
A quick usage note:
Application Support/BBedit/Text Filters/
could be~/Library/Application Support/BBEdit/Text Filters/
.