Update upstream repo url for `haskeline`

[hackage:haskeline] has now an official GitHub repo at
https://github.com/judah/haskeline.git

Consequently, there remain only 3 repos which are Darcs hosted
(and thus still require darcs2git mirroring), namely
[hackage:time], [hackage:terminfo], and [hackage:transformers].

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>