Release v0.12.10

• fix break in try-catch query (label $x | try break $x catch .)
• fix path value validation for getpath function (path(getpath([[0]][0])))
• fix path value validation for custom iterator functions
• fix walk function with argument emitting multiple values ([1],{x:1} | walk(.,0))
• fix @csv, @tsv, @sh to escape the null character (["\u0000"] | @csv,@tsv,@sh)
• improve performance of assignment operator (=), update-assignment operator (|=),
  map_values, del, delpaths, walk, ascii_downcase, and ascii_upcase functions