Adapt to v2 changes in productions runs endpoint

[daniel-k]

In both #47 and #55 we have missed breaking changes in the production runs endpoint of the v2 API:

• production runs don't contain the product resource anymore, but only a reference (UUID)
• product and production order "code" was renamed to "external id"

[github-actions]

Coverage results

Update on 2025-05-26 10:14:53.981495822 +0000

This is the coverage report for commit 80c5803

Name                                                               Stmts   Miss  Cover   Missing
------------------------------------------------------------------------------------------------
.tox/py/lib/python3.12/site-packages/enlyze/__init__.py                4      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/api_client/client.py      82      1    99%   143
.tox/py/lib/python3.12/site-packages/enlyze/api_client/models.py      85      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/auth.py                   13      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/client.py                105      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/constants.py               6      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/errors.py                  4      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/iterable_tools.py          7      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/models.py                117      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/schema.py                 25      0   100%
.tox/py/lib/python3.12/site-packages/enlyze/validators.py             38      0   100%
------------------------------------------------------------------------------------------------
TOTAL                                                                486      1    99%

2 empty files skipped.

[denizs]

Mini change request. Moreover, I've updated the example jupyter notebook and pushed the commit to this branch.