Static files inside subfolders are not accessible (404)

[mikekeda]

Describe the bug

After upgrading from 20.12.3 to 21.3.0 I'm getting 404 for all my static files (those files are located inside subfolders), example:
GET http://127.0.0.1:8000/static/node_modules/jquery/dist/jquery.min.js 404

but static files that are located directly inside static folder are accessible, example:
GET http://127.0.0.1:8000/static/package.json 200

Code snippet
I added static in this way (it was working fine for Sanic <= 20.12.3):
app.static("/static", "./static")

I'm assuming the problem is in this line:
uri += "/<__file_uri__>"
https://github.com/sanic-org/sanic/blob/master/sanic/mixins/routes.py#L779
looks like there is no place for subfolders

Expected behavior
I expect static files inside subfolders to accessible.

Environment (please complete the following information):

• OS: MacOS 11.2.3
• Version 21.3.0
• Python 3.9.0

Additional context
This is a problem only for local environment, for prod static files are not served by Sanic

[ahopkins]

😒 I knew there was bound to be some bug with such sweeping changes. I will work on a patch for this and get a 21.3.1 out as soon as I can. We need to add this to test coverage as well.