Fixup shebangs in the venv scripts so they at least work if you're in the same directory.

pkg/mac/build-functions.sh

@@ -85,6 +85,10 @@ _create_python_env() {
     done
     IFS=${OLD_IFS}
 
+    # Fixup shebangs
+    cd "${BUNDLE_DIR}/Contents/Frameworks/Python.framework/Versions/Current/bin"
+    grep -RiIl 'mac-build' * | xargs sed -i '' 's/\/.*\/python3\./.\/python3./g'
+
     # Remove some things we don't need
     cd "${BUNDLE_DIR}/Contents/Frameworks/Python.framework"
     find . -name test -type d -print0 | xargs -0 rm -rf