In the _setup_package_with_constraints_edit name of the package was
always discovered from the setup.cfg file. But as some projects
implements PEP-621 (see [1] for the SQLAlchemy for example) it is not
enough now.
This patch adds parsing pyproject.toml file also if name is not found in
the setup.cfg file.
[1] a8dbf8763a
Closes-Bug: #2052509
Change-Id: Iee9262079d09a8bd22cd05a8f17950a41a0d1f9d
4ddd456dd3