Fix: Replaced removeLast() with remove(current.size() - 1) (#6152)

Fix: Replaced removeLast() with remove(current.size() - 1) for compatibility with ArrayList

Author: MaddyRizvi

Diff for: src/main/java/com/thealgorithms/backtracking/ArrayCombination.java

@@ -48,7 +48,7 @@ private static void combine(List<List<Integer>> combinations, List<Integer> curr
         for (int i = start; i < n; i++) {
             current.add(i);
             combine(combinations, current, i + 1, n, k);
-            current.removeLast(); // Backtrack
+            current.remove(current.size() - 1); // Backtrack
         }
     }
 }