fix: use twine==4.0.2 in pypi release jobs

Fix #41 (closed)

What does this MR do?

Pins the version of twine to 4.0.2 in pypi release jobs. In principle, 5.0.0 might be stable, but the quickest fix is to use the LKG.

Does this by inlining the test-pypi-release and pypi-release jobs

Checks

1. Checked yaml changes against the pipeline editor on Full configuration view for pypi-release and test-pypi-release jobs: https://gitlab.developers.cam.ac.uk/uis/devops/iam/identity-lib/-/ci/editor?branch_name=main
2. Ran job in CI with rc1 version. Successfully pushed to test pypi: https://test.pypi.org/project/ucam-identitylib/3.3.1rc2/