taplo: add shell completions
- Version 0.10.0 of Taplo CLI added the ability to generate completions
for shells (see https://github.com/tamasfe/taplo/releases/tag/0.10.0).
- This commit adds the generated shell completions to the derivation
output.
- Resolves https://github.com/NixOS/nixpkgs/issues/440875.