Suggestion for URLs

[mariofix]

Hello, I'm trying your app and I noticed it creates a few routes /statics, /api/{identity}, they get added at the root.

INFO: 127.0.0.1:41598 - "GET /user/list HTTP/1.1" 200 OK
INFO: 127.0.0.1:41598 - "GET /api/user?skip=0&limit=10 HTTP/1.1" 200 OK
INFO: 127.0.0.1:56438 - "GET /api/user?skip=0&limit=10 HTTP/1.1" 200 OK

I believe they should be added after base_url=/admin so the URL always has /admin prepended.
I was about to make the fork and then the PR but I noticed you're about lo launch a new release, are you considering making this modification? I can make it if you didn't consider it for the new release.

[jowilf]

Hello,
starlette-admin create a mounted app into your original app with base_url as base root path.

It won't be visible in log due to this issue in starlette itself ->
encode/starlette#1336

Thank you.