a5e729da

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Let NixCI discover the CI dependency graph itself

NixCI can derive the job graph from the derivations it is asked to
build, so restating the Guppy crate graph in this file buys nothing and
costs plenty: 250 lines that have to be kept in step with the flake,
and an edge the file misses lets two jobs build the same derivation at
the same time, which we pay for twice.

Discovery runs synchronously, so no job starts before the graph is
known and those duplicates are never scheduled in the first place.

The manual graph was also doing much less than it looked like: of the
241 edges it computed, 160 touched a job in doNotBuild and were
dropped again by buildableDependencies before NixCI ever saw them.