tests/vm: use the default system python for NetBSD

tests/vm: use the default system python for NetBSD

Currently our NetBSD VM recipe requests instal of the python37 package
and explicitly tells QEMU to use that version of python. Since the
NetBSD base ISO was updated to version 9.3 though, the default system
python version is 3.9 which is sufficiently new for QEMU to rely on.
Rather than requesting an older python, just test against the default
system python which is what most users will have.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230329124601.822209-1-berrange@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230403134920.2132362-10-alex.bennee@linaro.org>