py-build: updated to 1.1.1

1.1.1 (2024-02-29)

Fixed invoking outer pip from user site packages
Corrected the minimum pip version required to use an outer pip

1.1.0 (2024-02-29)

Use external pip if available instead of installing, speeds up environment setup with virtualenv slightly and venv significantly.
Stopped injecting wheel as a build dependency automatically, in the case of missing pyproject.toml
Use importlib_metadata on Python <3.10.2 for bugfixes not present in those CPython standard libraries (not required when bootstrapping)

(adam)