[gtk-osx] Force using pip3.

[John Ralls <jralls src gnome org>]

commit 3c3b039538e87b329c4a1f9d7adb3717b8ab9604
Author: John Ralls <jralls ceridwen us>
Date:   Tue Feb 15 21:23:29 2022 -0800

    Force using pip3.
    
    Pyenv's pip shim is for python2's pip, don't want that.

 gtk-osx-setup.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gtk-osx-setup.sh b/gtk-osx-setup.sh
index 81bda9b..38bf202 100755
--- a/gtk-osx-setup.sh
+++ b/gtk-osx-setup.sh
@@ -98,7 +98,8 @@ fi
 export PYTHON_CONFIGURE_OPTS="--enable-shared"
 export PYENV_PYTHON_VERSION=3.10.0
 $PYENV install -v $PYENV_PYTHON_VERSION
-PIP="$PYENV_ROOT/shims/pip"
+PIP="$PYENV_ROOT/shims/pip3"
+
 $PIP install --upgrade --user pip
 
 # Install pipenv