python: Install pycotap in our venv if necessary

python: Install pycotap in our venv if necessary

The upcoming functional tests will require pycotap for providing
TAP output from the python-based tests. Since we want to be able
to run some of the tests offline by default, too, let's install
it along with meson in our venv if necessary (it's size is only
5 kB, so adding the wheel here should not really be a problem).

The wheel file has been obtained with:

 pip download --only-binary :all: --dest . --no-cache pycotap

Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20240830133841.142644-8-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>