Merge pull request #5516 from sjakobi/reenable-hnix

Re-enable hnix

build-constraints.yaml

@@ -481,7 +481,7 @@ packages:
         - coercible-utils < 0 # ghc 8.10
         - hspec-parsec
         - checkers
-        - hnix <0 # https://github.com/haskell-nix/hnix/issues/651
+        - hnix
         - hashing
         - hnix-store-core
         - monadlist
@@ -1121,7 +1121,7 @@ packages:
         - dhall-lsp-server
         - dhall-yaml
         - aeson-yaml  # req'd by dhall-json
-        # - dhall-nix # deriving-compat via hnix
+        - dhall-nix
 
     "Andrew Thaddeus Martin <andrew.thaddeus@gmail.com> @andrewthad":
         - colonnade < 0 # via profunctors-5.5