tmuxinator 2.0.3 fixes a compatibility warning with tmux 2.3, which is
the version packaged on NixOS 21.05.
See https://github.com/tmuxinator/tmuxinator/issues/814
(cherry picked from commit 28ab65b5869c6673e359093662a1dfe3aba9b829)
Keep the `source` attrset distinct to prevent its entries from merging
with the top level attrs.
Since each type of source has a different set of entries for `source`,
this is the easiest way to keep them together.
This will pave the way for a new `url` type of source.
This is a mass-rebuild of many ruby packages,
notably those using `git` type sources.