python3-pytest-subtests: upgrade 0.12.1 -> 0.13.0

python3-pytest-subtests: upgrade 0.12.1 -> 0.13.0

Changelog (https://github.com/pytest-dev/pytest-subtests/blob/main/CHANGELOG.rst):

- Dropped support for EOL Python 3.7.
- Added support for -x/--exitfirst (#134).
- Hide the traceback inside the SubTests.test() method (#131).

The tarball changed to use an underscore instead of a dash, so use
PYPI_PACKAGE to account for it.

Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>