Update sphinx_rtd_theme to 68a19ca / 0.4.3.dev0.

[Chris Johns]

On 23/2/20 12:39 pm, Amar Takhar wrote:
> I've been running this version for a while now.  It should fix any issues we're 
> having I tested it and it works fine.
> 
> See here for a ticket the patch is rather large:
> 
>   https://devel.rtems.org/ticket/3880
> 

Does this work on sync.rtems.org with a suitable virtualenv?

This is how I build the online docs. :)

Chris