fix: resolve checkstyle issues (newline, imports, inner assignment)

Author: prashantpiyush1111

src/main/java/com/thealgorithms/datastructures/queues/ThreadSafeQueue.java

@@ -44,4 +44,4 @@ public synchronized T dequeue() {
 	public synchronized boolean isEmpty() {
 		return head == null;
 	}
-}
+}