Release 3.0 beta 0

This is a beta release.

• Rewrite of script to Python (#39). Includes unit tests, updated documentation, and Github actions to automate those. This is a breaking change when it comes to users who have set up configuration files. Previously each snapper configuration would require its own snap-pac configuration file. Now these are all combined into a single configuration file located at /etc/snap-pac.ini with each snapper configuration having its own section. See the configuration section of the documentation for more information.
• Adds a couple of new options for the configuration files including important_packages and important_commands. Both of these should be arrays of strings. These are used to specify when the important=yes userdata is added to a snapshot. Resolves #38. See the configuration section of the documentation for more information.
• Additional userdata can now be added by using the userdata configuration option. This is an array of strings, with each string containing key-value pairs. See the configuration section of the documentation for more information.