Fix email issue

src/main.py

@@ -19,12 +19,18 @@ def get_db():
 
 @app.post("/users/", response_model=User)
 def create_user(user: UserCreate, db: Session = Depends(get_db)):
-    db_user = crud.get_user_by_email(db, email=user.email)
+    db_user = crud.get_user_by_username(db, username=user.username)
     if db_user:
         raise HTTPException(status_code=400, detail="Email already registered")
     return crud.create_user(db=db, user=user)
 
 
+@app.get("/users/", response_model=list[User])
+def read_users(db: Session = Depends(get_db)):
+    users = crud.get_users(db)
+    return users
+
+
 @app.get("/")
 async def root():
     return {"message": "Hello World"}