title: Not able to click nb-checkbox of Nebular theme angular
body: <p>I am new to Nebular theme. I have a checkbox but it's not working.</p>
  
  <p>HTML</p>
  
  <pre><code>&lt;nb-checkbox [value]="checked" (change)="toggle($event)"&gt;&lt;/nb-checkbox&gt;
  </code></pre>
  
  <p>TypeScript</p>
  
  <pre><code>  toggle(checked: any) {    
      this.checked = checked.target.checked;
    }
  </code></pre>
  
  <p>Module.ts</p>
  
  <pre><code>//import
  import { NbCheckboxModule } from '@nebular/theme';
  
  imports: [NbCheckboxModule]
  </code></pre>
  
  <p>toggle function is being called fine but checkbox is not being checked. </p>
  
  <p>I have been debugging since a long time but couldn't identify the issue. Any suggestions about what could be wrong? Thank you.</p>
  
  <p>Angular Version: 7.1</p>
  
  <p>Nebular version: ^3.5.0</p>