meson: don't bother trying `python2`

Meson requires `python3`, so we know it's there, no need to fall back to
python2.

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3701>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3701>
1 file changed