Set MACOSX_DEPLOYMENT_TARGET when running script/bundle

This ensures that every library and binary we build doesn't assume
that it's going to run on the same machine that created it.

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

script/bundle

@@ -3,6 +3,7 @@
 set -e
 
 export ZED_BUNDLE=true
+export MACOSX_DEPLOYMENT_TARGET=10.14
 
 echo "Installing cargo bundle"
 cargo install cargo-bundle --version 0.5.0