Stegano

- Stegano now uses Pillow 9.0.0 (CVE-2022-22815).

- Stegano now uses OpenCV Python 4.5.4 abd Numpy 1.21.4.

- new: Implemented Shi-Tomashi corner generator
([PR 32](https://github.com/cedricbonhomme/Stegano/pull/32)).
Implemented by thundersparkf (see CONTRIBUTORS.md file).

- Stegano now uses Pillow 8.3.0.

- Stegano is now using poetry;
- minor improvements to the command line.

- fixed markdown of the previous release.