Fix circle_area function

drone_test/_circle_area.py

@@ -7,7 +7,7 @@ def circle_area(radius: float):
     :raises ValueError: radius is negative
     :return: area of the circle
     """
-    #if radius < 0:
-        #raise ValueError("Circle can't have negative radius")
+    if radius < 0:
+        raise ValueError("Circle can't have negative radius")
 
     return math.pi * radius ** 2