added another algorithm

Author: Chiefpatwal

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

@@ -1,7 +1,6 @@
 package com.thealgorithms.slidingwindow;
 import java.util.HashSet;
 
-
 /**
  * The Longest Substring Without Repeating Characters algorithm finds the length of
  * the longest substring without repeating characters in a given string.

src/test/java/com/thealgorithms/slidingwindow/LongestSubstringWithoutRepeatingCharactersTest.java

@@ -1,8 +1,9 @@
 package com.thealgorithms.slidingwindow;
 
-import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import org.junit.jupiter.api.Test;
+
 /**
  * Unit tests for the LongestSubstringWithoutRepeatingCharacters class.
  *