Address deprecation warnings

• Address some deprecations warnings thanks to @pdxmph
• CI housekeeping: move to GHA from travis

1.1: Cache Improvements

• Adds aggressive caching to reduce rebuild times.
  If you need to re-render images for any reason, remove the .jekyll-cache folder or change the _config.yml file.

• Changes default quality to 85, and instead strips alls comments.
  This results in better quality pictures with less size.

1.0: Stable Release

This is the first production ready release. With this, I commit to a stable behaviour.