Release v2.1.0

• Added: audeer.unique(),
  which returns unique values
  in the order they appear in a sequence
• Added: maximum_refresh_time argument
  to audeer.progress_bar()
  and audeer.run_tasks(),
  which can be used
  to force an update interval
  of the progress bar
• Fixed: documentation of return value
  of audeer.run_tasks()