r2dii.data 0.3.0

• New dataset abcd_demo supersedes the dataset ald_demo (#279).
• region_isos gains data for new scenario sources: 'weo_2021', 'etp_2020',
  'geco_2020' and 'geco_2021'.
• region_isos gains country specific regions for 'weo_2019' and 'weo_2020'
  (#270 @julie-vienne).