[icudotnet] Use https instead of git
[icudotnet] Use https instead of git

Some build agents in Calgary redirect `git://github.com` repos to
a local repo. The icu-dotnet repo isn't mirrored in Calgary so
this fails. Instead we use the https protocol which isn't redirected
in Calgary.

Change-Id: I401238791c3b43bc70efd21ec0d526a5230b22c6

sillsdev/ci-builder-scripts,sillsdev/ci-builder-scripts,sillsdev/ci-builder-scripts