CI: add miri test; chore (#240)
* CI: add miri test; new phase; remoe CARGO_HOME cache
* add miri and falgs to test
* Update .gitlab-ci.yml
Co-authored-by: 
Guillaume Thiolliere <gui.thiolliere@gmail.com>
* CI: add miri test; new phase; remoe CARGO_HOME cache
* add miri and falgs to test
* Update .gitlab-ci.yml
Co-authored-by: Guillaume Thiolliere <gui.thiolliere@gmail.com>