Addressing #1395 but with a different solution from #1478, using
semantic versioning based on implementation found
[here](https://distresssignal.org/busting-css-cache-with-jekyll-md5-hash).
Implemented a way of calculating the hash for both a single file or
directory. This way we can calculate the hash for when there is a change
in the `_sass` dir, for example, or in the contents of a single file.
Examples of generated outputs of the plugin:
```
/al-folio/assets/css/main.css?d41d8cd98f00b204e9800998ecf8427e
/al-folio/assets/js/theme.js?96d6b3e1c3604aca8b6134c7afdd5db6
/al-folio/assets/js/dark_mode.js?9b17307bb950ffa2e34be0227f53558f
/al-folio/assets/js/no_defer.js?d633890033921b33e0ceb13d22340a9c
/al-folio/assets/js/common.js?acdb9690d7641b2f8d40529018c71a01
/al-folio/assets/js/copy_code.js?c9d9dd48933de3831b3ee5ec9c209cac
/al-folio/assets/img/prof_pic.jpg?974957d202f671e4fa6700c04e68deae
```
Signed-off-by: George Araujo <george.gcac@gmail.com>
This PR replaces the jekyll-responsive-images with jekyll-imagemagick for responsive WebP images.
WebP images are much smaller compared to PNG and JPEG, faster to load and most of the modern browsers recommend it.
More information about WebP images: https://developers.google.com/speed/webp