Dub project owner change

[Richard Andrew Cattermole (Rikki)]

It has come to my attention that the project ownership of dub 
changed hands a few years ago to Mathias Lang from Sönke Ludwig.
No announcement occurred at the time, which is a governance 
failure, so I get to do it.

Over the last couple of years, Mathias has made many improvements 
to dub; here are some highlights:

- Better error messages (pkg-config)
- Housekeeping tasks to keep the CI happy
- Improved performance i.e. GC usage
- dub fetch supports multiple arguments, recursive fetch, and is 
more project-aware
- Remove support for OMF

So I want to thank Sönke for his prior work on dub, and 
congratulate Mathias on his prior and continuing work in 
maintaining dub!

Me and Nic will soon begin work to triage the existing PR's and 
bug reports over the coming days to try and get the development 
experience of contributing to a dlang repository more in line 
with expectations.