Added test case "AAABBC" "AABC"

Author: Anubhav-pandey004

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

@@ -30,5 +30,6 @@ public void testMinimumWindowSubstring() {
         assertEquals("ABCDEFG", MinimumWindowSubstring.minWindow("ABCDEFG", "ABCDEFG"));
         assertEquals("", MinimumWindowSubstring.minWindow("abc", "A"));
         assertEquals("A", MinimumWindowSubstring.minWindow("aAbBcC", "A"));
+        assertEquals("AABBC", MinimumWindowSubstring.minWindow("AAABBC", "AABC"));
     }
 }