Update of gnurl to 7.60.0

Since the release email is still to be published, here's the sha512sums:

cdfa6cf5d576b7db63612bf77c2bb0d03dbde143dbf1c61f8fbab526e7c20bf46ac13df44babaa8a0d8ab78b38ca30d50c944e3c1843043c5fbd07553a00ffcb  gnurl-7.60.0.tar.gz
d9fedd41d3b55ff723793c19cb79001cee413773fe7d404dacdf07a1663c7eca03a5e5c2e7f86ebdc1fd0f5afb2d8c477c5967587acab2fda97bca4476f47c86  gnurl-7.60.0.tar.Z

I noticed an error in the testsuite while offloading the build. Locally
it builds fine.
If you encounter a bug, please report it to our Mantis bugtracker (https://gnunet.org/bugs)
or the bugs mailinglist of GNUnet.

Thanks