Bumped send_file() to HTTP/1.1, added missing zero-length chunk at the end

[VirtualWolf]

I was playing around with this on my ESP32 and curl was giving output like this:

[virtualwolf@twee:~]$ curl -v http://indoor/log
*   Trying 10.0.1.102...
* TCP_NODELAY set
* Connected to indoor (10.0.1.102) port 80 (#0)
> GET /log HTTP/1.1
> Host: indoor
> User-Agent: curl/7.64.1
> Accept: */*
>
< HTTP/1.0 200 OK
< Content-Type: text/html
< Content-Length: 283
< Accept-Ranges: none
< Transfer-Encoding: chunked
<
[content of the file it's loading, snipped for brevity]
* Illegal or missing hexadecimal sequence in chunked-encoding
* Closing connection 0
curl: (56) Illegal or missing hexadecimal sequence in chunked-encoding

It turns out there were two issues, one is that chunked encoding is available in HTTP/1.1, not 1.0, and it requires a final zero-length chunk to indicate there's no more.

(As an aside, thanks so much for this repo, it's been invaluable in getting my head around how to use uasyncio to create a super-basic HTTP server!)

[marcidy]

Thanks! Nice catch, appreciate the fix!