Fix test pypi worflow

[kratman]

Description

Updates to the test pypi workflow.

Fixes #3904

Type of change

• [x] Bug fix (non-breaking change which fixes an issue)

Key checklist:

• [x] No style issues: $ pre-commit run (or $ nox -s pre-commit) (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• [x] All tests pass: $ python run-tests.py --all (or $ nox -s tests)
• [x] The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

You can run integration tests, unit tests, and doctests together at once, using $ python run-tests.py --quick (or $ nox -s quick).

Further checks:

• [x] Code is commented, particularly in hard-to-understand areas
• [x] Tests added that prove fix is effective or that feature works

[kratman]

I made some of the changes in the workflow, but have not updated anything on PyPi yet. I will mark this as ready for review once the PyPi changes are made and I test the new workflow

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.54%. Comparing base (6a0cd9a) to head (f644980).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #4217 +/- ## ======================================== Coverage 99.54% 99.54% ======================================== Files 288 288 Lines 21886 21886 ======================================== Hits 21786 21786 Misses 100 100 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[kratman]

@Saransh-cpp, @agriyakhetarpal I removed this as a release blocker, because we will need to get the old testpypi project transferred to PyBaMM-Team. Transferring projects when the maintainer is not reachable takes 6 weeks. @brosaplanella is trying to reach them

[kratman]

@tlestang Can you help me with transferring the testpypi account?