fix: missing dependency on example flake.nix

[dukc]

No description provided.

[github-actions]

Thanks for your Pull Request!

Below you will find a summary of the cachix status of each package, for each supported platform.

package	x86_64-linux	x86_64-darwin	aarch64-darwin
dmd	✅ cached	✅ cached	🚫 not supported
dmd-2_096_1	✅ cached	✅ cached	🚫 not supported
dmd-2_098_1	✅ cached	✅ cached	🚫 not supported
dmd-2_100_2	✅ cached	✅ cached	🚫 not supported
dmd-2_102_2	✅ cached	✅ cached	🚫 not supported
dmd-2_103_1	✅ cached	✅ cached	🚫 not supported
dmd-2_104_2	✅ cached	✅ cached	🚫 not supported
dmd-2_105_2	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_079_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_080_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_081_2	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_082_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_083_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_084_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_085_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_086_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_087_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_088_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_089_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_090_1	✅ cached	✅ cached	🚫 not supported
dmd-binary-2_098_0	✅ cached	✅ cached	🚫 not supported
dmd-bootstrap	✅ cached	✅ cached	🚫 not supported
dub	✅ cached	✅ cached	✅ cached
dub-1_30_0	✅ cached	✅ cached	✅ cached
ldc	✅ cached	🚧 known to fail (disabled)	🚧 known to fail (disabled)
ldc-1_30_0	✅ cached	🚧 known to fail (disabled)	🚧 known to fail (disabled)
ldc-binary	✅ cached	✅ cached	✅ cached
ldc-binary-1_19_0	✅ cached	✅ cached	🚫 not supported
ldc-binary-1_25_0	✅ cached	✅ cached	✅ cached
ldc-binary-1_28_0	✅ cached	✅ cached	✅ cached
ldc-binary-1_32_1	✅ cached	✅ cached	✅ cached
ldc-binary-1_34_0	✅ cached	✅ cached	✅ cached

[dukc]

As this is trivial, I'm merging right away. Please revert if there was a mistake.

[PetarKirov]

LGTM, thanks for the fix 👍