Bump letter_opener from 1.4.1 to 1.6.0 (#1353)
Bump letter_opener from 1.4.1 to 1.6.0 (#1353)

Bumps [letter_opener](https://github.com/ryanb/letter_opener) from 1.4.1 to 1.6.0.
- [Changelog](https://github.com/ryanb/letter_opener/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ryanb/letter_opener/compare/v1.4.1...v1.6.0)
tablexi/nucore-open,tablexi/nucore-open,tablexi/nucore-open,tablexi/nucore-open