fix(ci): ensure pip is always available (#138)

Author: stainless-app[bot]

bin/publish-pypi

@@ -5,5 +5,6 @@ mkdir -p dist
 rye build --clean
 # Patching importlib-metadata version until upstream library version is updated
 # https://github.com/pypa/twine/issues/977#issuecomment-2189800841
+"$HOME/.rye/self/bin/python3" -m ensurepip
 "$HOME/.rye/self/bin/python3" -m pip install 'importlib-metadata==7.2.1'
 rye publish --yes --token=$PYPI_TOKEN