message: [gbc] Temporarily pin derive dependency to < 2.6
  gbc-tests no longer builds with derive 2.6 or later. While we
  investigate that problem, pin the dependency to < 2.6 to keep gbc-tests
  building.
  Mitigates
diff: @@ -91,7 +91,7 @@ test-suite gbc-tests
  filepath >= 1.0,
  monad-loops >= 0.4,
  text >= 0.11,
  - derive,
  + derive < 2.6,
  HUnit,
  QuickCheck,
  Diff >= 0.2 && < 0.4,
  