comply with official django async orm syntax

when we patch models, we prefix the methods with `async_`  but the new official django api prefixes the methods with `a` ex:

patched api : sync `objects.get`  => async `objects.async_get`
official api:  sync `objects.get`  => async `objects.aget`

so to make it forward compatible we need to comply to django's new api.

be aware to keep our api so we don't break the internet