[Ur] build errors in travis

[Adam Chlipala]

Good catch!  Now I'm curious why the CI system didn't tip me off about 
this problem earlier, but it should be fixed now.

On 3/30/21 3:03 AM, Fabrice Leal wrote:
> Decided to check again on urweb, and noticed the build error mark on 
> the readme; after some light investigation it seems the error comes 
> from building the demo application, which has a bunch of
>
> allow url #*
>
> is this new syntax or obsolete syntax? :)