Update MinimumWindowSubstring.java

Author: Anubhav-pandey004

src/main/java/com/thealgorithms/slidingwindow/MinimumWindowSubstring.java

@@ -1,5 +1,5 @@
 package com.thealgorithms.slidingwindow;
-import java.util.*;
+import java.util.HashMap;
 /**
  * The Longest Subarray with Sum Less Than or Equal to k algorithm finds the length
  * of the longest subarray whose sum is less than or equal to a given value k.