fix: issue with shared memory for updated yaml nodes

[ThomasRooney]

An overlay like:

overlay: 1.0.0
x-speakeasy-jsonpath: rfc9535
info:
    title: example overlay
    version: 0.0.0
actions: 
  - target: $.paths.*.*
    update: 
      x-drop: true
  - target: $.paths.*[?@.operationId == 'findPetsByStatus']
    update:
      x-drop: false

Would previously re-use memory for x-drop: true across the document, which means that subsequent updates would affect all nodes.

This makes sure we clone the yaml node before inserting it into the document.