simmer 4.4.7

New features

• Add support for subsetting by activity tag (#305).
• New getter get_start_time() returns the running arrival's start time (#304).

Minor changes and fixes

• Fix set_source() to avoid leaking arrivals from the old source (#322).
• Fix sources to properly reset distributions and trajectories (#324).
• Fix resources to properly reset initial parameters (#325).
• Fix start time of arrivals in cloned batches (#285).