fix: add spaces after comment slashes

Author: Rosander0

src/test/java/com/thealgorithms/strings/LongestCommonSubstringTest.java

@@ -1,5 +1,5 @@
 package com.thealgorithms.strings;
-//author: Vraj Prajapati @Rosander0
+// author: Vraj Prajapati @Rosander0
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import org.junit.jupiter.api.Test;