Release 0.5.4

- `Assert::with_env` for setting environment variables

Release v0.5.3

- Support writing to `stdin`

Release 0.5.2

- Show stdout/stderr on exit code failures
- Show expected/got strings for output assertions

Release 0.5.1

- Reduce unnecesary rebuilds due to skeptic.

Release 0.5.0

This release includes
- Changing output asserts
  - `.prints` -> `.stdout().contains`
  - `.prints_exactly` -> `.stdout().is`
  - `.prints_error` -> `.stderr().contains`
  - `.prints_error_exactly` -> `.stderr().is`
- Add negative output assertions
  - `.stdout().isnt`
  - `.stdout().doesnt_contain`
- Output assertions are now anded together rather than replacing each
  other.

Add more Cargo metadata