otelerr/v1.0.1

External review round 7 finding.

• Fixed RecordSpan no longer lets a With attr sharing the reserved
  "errtrail.code" key duplicate the taxonomy attribute on the exported
  exception event. A duplicate key's resolution (first-wins, last-wins, or
  an array) varies by tracing backend — an accidental or hostile attr named
  errtrail.code could silently corrupt the one attribute alerts and
  dashboards key off of. The attr is now dropped; the real code always
  wins. No core requirement change.