v3.0.0

There are breaking changes in this release, and you may have to update your
scripts to use this version.

Breaking Changes

The main (and only) breaking change in this release is an overhaul of the BOM
generation utility function
allspice.utils.bom_generation.generate_bom_for_altium. The changes are:

1. generate_bom_for_altium no longer takes a PcbDoc file as an argument. The
   BOM generation logic has been reworked to only use a PrjPcb file as the sole
   entrypoint and generate the entire BOM from the schematics.

   See #83

2. You can now customize the columns of the BOM and how rows are grouped using
   the columns and group_by arguments. This replaces the former
   attributes_mapping argument.

   For example, if you want to have columns "Comment", "Part ID" and
   "Manufacturer" in your BOM and group them by the "Part ID", you would pass:

   generate_bom_for_altium(
      # ...
      columns={
        "Comment": ["Comment", "Description", "_description"],
        "Part ID": "_part_id",
        "Manufacturer": ["Manufacturer", "MFN"],
      },
      group_by=["Part ID"],
   )

   This also shows the _description and _part_id attributes which are
   populated from the component itself.

   See #84

3. BOM generation now supports variants, and you can select which variant to
   generate a BOM for using the variant argument.

   See #86

Other changes

The example scripts for BOM generation and COGS generation have also been
updated to work with these new changes.