title: ngf-pattern not working for ng-file-upload
body: <p>I am trying to limit the file type to CSV in the <code>ng-file-upload</code> component but it isn't working - it still accepts all files.</p>
  
  <p>I have tried both <code>ngf-pattern="'*.csv'"</code> and <code>ngf-pattern="*.csv"</code>.</p>
  
  <p>Code:</p>
  
  <pre><code>   &lt;button class="btn btn-info" type="file" ngf-select="uploadFiles($file, $invalidFiles)"
                          ngf-pattern="'*.csv'" ngf-max-height="1000" ngf-max-size="1MB"&gt;
                      &lt;i class="fa fa-upload"&gt;&lt;/i&gt; {{'main.users.import.button' |translate}} &lt;/button&gt;
  </code></pre>
  
  <p>Dependency:</p>
  
  <pre><code>  "ng-file-upload": "~10.0.2",
  </code></pre>