Add missing ripple

app/src/main/java/com/hippo/ehviewer/shortcuts/ShortcutsActivity.java

@@ -16,21 +16,22 @@
 
 package com.hippo.ehviewer.shortcuts;
 
-import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 
+import androidx.appcompat.app.AppCompatActivity;
+
 import com.hippo.ehviewer.download.DownloadService;
 
 /**
  * Created by onlymash on 3/25/18.
  */
 
-public class ShortcutsActivity extends Activity {
+public class ShortcutsActivity extends AppCompatActivity {
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
-        String action = null;
+        String action;
         Intent intent = getIntent();
         if (intent != null) {
             action = intent.getAction();