fix: remove self arg from system router

Author: TimNekk

app/system/router.py

@@ -5,11 +5,11 @@
 
 
 @system_router.get("/", include_in_schema=False)
-async def root(self) -> dict[str, str]:
+async def root() -> dict[str, str]:
     return {"message": "MusicBox API"}
 
 
 @system_router.get("/health", include_in_schema=False)
-async def health(self) -> JSONResponse:
+async def health() -> JSONResponse:
     data = {"music-box-api": status.HTTP_200_OK}
     return JSONResponse(data, status_code=status.HTTP_200_OK)