Isolate tests with minimum version

[HideakiImamura]

Motivation

To fix the CI.

The latest release of setuptools breaks the installation of libraries using numpy.distutils. See pypa/setuptools#3693 and numpy/numpy#22623.

This PR suggests to avoid the latest setuptools when we use libraries using numpy.distutils, that is, the tests with minimum versions. This is a temporary fix. We don't have to avoid the latest setuptools for normal tests, so I isolate the normal tests and those with minimum versions.

The merits of this isolation are as follows.

• As the current problem suggests, tests with minimum versions are fragile. It is possible for a version unspecified library update to cause a test to fail at an unexpected time. By splitting up the workflow, when a test fails, it becomes clear whether the problem is with tests with minimum versions or not.
• In addition, in the current GitHub Actions configuration, normal tests are required, but tests with minimum versions are not. If they are in the same workflow, a failure of tests with minimum versions may cause the entire workflow to be canceled and the required tests to not be executed.

Description of the changes

• Isolate the normal tests and tests with minimum versions.
• Add version constraint setuptools<65.6.0 for tests with minimum versions.