Package Release Not Found

Hi. I hope you can help me with this. When I run your build command I get the the following error

```
+ hg clone -r 1.18.0-2~buster https://hg.nginx.org/pkg-oss/
destination directory: pkg-oss
abort: unknown revision '1.18.0-2~buster'!
```
(I tried stable instead of mainline but no luck)

I have used your Dockerfile and added the module `ngx_http_sub_module`.