testing/libdap: fix url & src
Upstream never replied to my email so switching to src to github.
Edited by TBK
We are currently working on getting Alpine Linux 3.21 out. This means that merge requests that are not aimed to help with that (only affecting testing, new aports) have a lower priority at the moment. Please be patient, they will be eventually picked up.
Upstream never replied to my email so switching to src to github.