[gtk-osx] Silence the python 2.7 deprecation warning.

[John Ralls <jralls src gnome org>]

commit e420971f8048edc7355ed649641e52c925417a2c
Author: John Ralls <jralls ceridwen us>
Date:   Tue Jul 30 14:33:28 2019 -0700

    Silence the python 2.7 deprecation warning.

 gtk-osx-setup.sh | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gtk-osx-setup.sh b/gtk-osx-setup.sh
index 98bf881..f6775c7 100755
--- a/gtk-osx-setup.sh
+++ b/gtk-osx-setup.sh
@@ -47,6 +47,7 @@ envvar PYENV_INSTALL_ROOT "$DEV_SRC_ROOT/pyenv"
 envvar PYENV_ROOT "$DEVPREFIX/share/pyenv"
 envvar PIP_CONFIG_DIR "$HOME/.config/pip"
 
+export PYTHONWARNINGS=ignore:DEPRECATION::pip._internal.cli.base_command
 export PYTHONPATH="$PYTHONUSERBASE/lib/python/site-packages":"$PYTHONPATH"
 
 if test ! -d "$DEVPREFIX/bin" ; then