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>
diff --git a/meson.build b/meson.build
index c48945b..9d9f303 100644
--- a/meson.build
+++ b/meson.build
@@ -22,7 +22,7 @@
   'mesa',
   ['c', 'cpp'],
   version : run_command(
-    [find_program('python', 'python2', 'python3'), 'bin/meson_get_version.py']
+    [find_program('python', 'python3'), 'bin/meson_get_version.py']
   ).stdout(),
   license : 'MIT',
   meson_version : '>= 0.46',