fix back icon

src/app/lobby/lobby.component.html

@@ -78,7 +78,7 @@
     <br>决斗数据库</a></mat-grid-tile>
   <mat-grid-tile>
     <button mat-raised-button (click)="ygopro.backHome()">
-      <mat-icon>sensor_door</mat-icon>
+      <mat-icon>home</mat-icon>
       <br>返回直连
     </button>
   </mat-grid-tile>