Update header.html: remove stray end tag

[l33d4n]

Remove stray end tag 'div'

[vsoch]

I'm not sure this is correct - as you have it now, the last block has two opening divs and only one closing:

	<div class="navbar-nav d-none d-lg-block">
          <a class="gh-source" data-gh-source="github" href="{{ site.repo }}" title="Go to repository" data-md-state="done">
          <div class="gh-source__repository">
            <i class="fab fa fa-github fa-2x" style='padding-right:20px; float:left; margin-top:5px'></i>
            {{ site.github_user }}/{{ site.github_repo }}
          <ul class="gh-source__facts"><li class="gh-source__fact" id='stars'></li><li id="forks" class="gh-source__fact"></li></ul></a>
        </div>

[l33d4n]

You're right, sorry. I removed the wrong div.