Bumps [react-dom](https://github.com/facebook/react/tree/HEAD/packages/react-dom) from 16.2.0 to 16.4.2.
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/master/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/v16.4.2/packages/react-dom)
Signed-off-by: dependabot[bot] <support@github.com>

Bumps [mixin-deep](https://github.com/jonschlinkert/mixin-deep) from 1.3.1 to 1.3.2.
- [Release notes](https://github.com/jonschlinkert/mixin-deep/releases)
- [Commits](https://github.com/jonschlinkert/mixin-deep/compare/1.3.1...1.3.2)
Signed-off-by: dependabot[bot] <support@github.com>

* .travis.yml: use cachix

* .travis.yml: fix locale issues with Nix

* .travis.yml: push to cachix

* .travis.yml: use latest NixOS

* .travis.yml: test notebook conversion with GHC 8.6

* test/acceptance.nbconvert.sh: ignore different line numbers for HLint

stack.yaml: enable IHaskell display packages