feat: EmptyDequeException 작성

Author: ksundong

yoonexample/src/main/java/exception/EmptyDequeException.java

@@ -0,0 +1,8 @@
+package exception;
+
+public class EmptyDequeException extends RuntimeException {
+
+  public EmptyDequeException() {
+    super("Deque is Emtpy.");
+  }
+}