Add option for single image

The tool now also supports resizing a single image instead of always browsing through the whole directory

v1.1.1 Bug fix - missing Gifsicle

Forgot to install Gifsicle in the container. That's fixed now.

Full Changelog: v1.1.0...v1.1.1

v1.1.0 Some refactoring

Using with instead of env now

Full Changelog: v1.0.0...v1.1.0

🚀 First release

Full Changelog: https://github.com/TheGroundZero/image-shrinker/commits/v1.0.0