Tidy up and fix build dependency loop
    
    - Haven't needed to fix documentation character encoding since 0.79
    - Drop Test::Base build dependency again to avoid a BR loop (#215637)
    - Filter private provides perl(yaml_mapping), perl(yaml_scalar) and
      perl(yaml_sequence)
    - Don't need to remove empty directories from the buildroot
    - This release by MSTROUT -> update source URL