remove input and output weights from convert function

[crdanielbusch]

Pull request

Please confirm that this pull request has done the following:

• Tests added
• Documentation added (where applicable)
• Description in a {pr}.thing.md file in the directory changelog added - see changelog/README.md for details

Description

This pull request builds on #281 which should be merged first. Removes the input_weights and output_weights from the convert function and raise errors if downscaling would be necessary.

At this point only one-to-one, and many-to-one conversions are possible.

In #284 support for one-to-many conversions is added again.

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 96.80%. Comparing base (bd02bd3) to head (ae21fe8).
Report is 8 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
primap2/_convert.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #282      +/-   ##
==========================================
- Coverage   96.98%   96.80%   -0.18%     
==========================================
  Files          49       49              
  Lines        4603     4598       -5     
==========================================
- Hits         4464     4451      -13     
- Misses        139      147       +8     

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[JGuetschow]

Looks good.