change(poetry): use kevr@upgrade-starlette-0.17.0 as fastapi source

Starlette 0.16.0 has a pretty bad bug in terms of logging which has been fixed in the 0.17.0 release. That being said, FastAPI has not yet merged a request at https://github.com/tiangolo/fastapi/pull/4145 which resolves this dependency resolution so we can use the updated starlette package.

kevr has forked the pull request in question and we are using it for now in our poetry dependencies to get ahead of the game.

When FastAPI upstream is updated to support 0.17.0, we'll need to switch this back to using upstream's source.

Signed-off-by: Kevin Morris kevr@0cost.org