v1.7.0

• Always clean up exploded pex files when exiting the Python entry point
  (#142)
• python_test: add env parameter (#140)
• python_test: make in-repo interpreter available to test at runtime
  (#141)
• Add plugin configuration option require_licences, which controls
  whether the licences parameter is mandatory for pip_library and
  python_wheel (#128)
• Upgrade coverage to 7.5.0 (#139, #144)