knapsack: Fix symbol

`new_seq` should be `newSeq`

Author: siebenschlaefer

exercises/practice/knapsack/.meta/example.nim

@@ -1,7 +1,7 @@
 type Item = tuple[weight: int, value: int]
 
 proc maximumValue*(maximumWeight: int, items: openArray[Item]): int =
-    var dp = new_seq[int](maximumWeight + 1)
+    var dp = newSeq[int](maximumWeight + 1)
     for item in items:
         for weight in countdown(maximumWeight, item.weight):
             dp[weight] = max(dp[weight], item.value + dp[weight - item.weight])