Revert "Use alertdialog.builder"

This reverts commit 97fbe73edf.

app/src/main/java/com/hippo/ehviewer/ui/MainActivity.java

@@ -43,10 +43,10 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.annotation.StringRes;
-import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.app.AppCompatDelegate;
 import androidx.drawerlayout.widget.DrawerLayout;
 
+import com.google.android.material.dialog.MaterialAlertDialogBuilder;
 import com.google.android.material.navigation.NavigationView;
 import com.google.android.material.snackbar.Snackbar;
 import com.hippo.app.EditTextDialogBuilder;
@@ -409,7 +409,7 @@ public final class MainActivity extends StageActivity
         if (null == uniFile || uniFile.ensureDir()) {
             return;
         }
-        new AlertDialog.Builder(this)
+        new MaterialAlertDialogBuilder(this)
                 .setTitle(R.string.waring)
                 .setMessage(R.string.invalid_download_location)
                 .setPositiveButton(R.string.get_it, null)