Java: Fix typo detected by @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: IdrissRio

java/ql/test/library-tests/compact-source-files/Test.java

@@ -23,5 +23,5 @@ static void testStaticAccess() {
 }
 
 class NotCompact {
-//Test explict class
+//Test explicit class
 }