Without this change, the build fails with:
```
Warning:
This package indirectly depends on multiple versions of the same package. This is very likely to cause a compile failure.
package hackage-db (hackage-db-2.0.1-AliTRXEJBGFAEMpONOEnbV) requires Cabal-2.4.0.1
package hpack (hpack-0.32.0-1iJuukTWmC4EGkYhAiFeII) requires Cabal-3.0.0.0-CD1INMNwoxXIKVgcu1nec5
package distribution-nixpkgs (distribution-nixpkgs-1.3.1-82Z2DCdLAUs8Q2gjtlPLz5) requires Cabal-3.0.0.0-CD1INMNwoxXIKVgcu1nec5
package cabal2nix (cabal2nix-2.15.0) requires Cabal-3.0.0.0-CD1INMNwoxXIKVgcu1nec5
package cabal2nix (cabal2nix-2.15.0) requires Cabal-3.0.0.0-CD1INMNwoxXIKVgcu1nec5
package cabal2nix (cabal2nix-2.15.0) requires Cabal-3.0.0.0-CD1INMNwoxXIKVgcu1nec5
```
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